On December 1, 1989, a new chapter of Griswold family dysfunction was unleashed upon the world when National Lampoon's Christmas Vacation made its debut in movie theaters and an instant holiday classic was born. Here are some things you might not know about everyone’s favorite Christmas comedy.

1. The movie is based on a short story.

Like the 1983 original, Christmas Vacation is based on a short story, “Christmas ’59,” written by John Hughes for National Lampoon in December 1980. Its literary predecessor is paid tribute to when Clark is trapped in the attic and pulls out a box of old home movies, including one labeled “Christmas ’59.” (Eagle-eyed viewers might notice that when Clark is watching the film, it actually says “Christmas 1955.”)

2. Clark Griswold grew up in Samantha Stevens’s house.

If Clark’s childhood home featured in those old movies looks familiar, that’s because it’s the same house featured on Bewitched as well as The New Gidget. Except it’s not a house at all; it’s part of the Warner Bros. back lot, located on what is known as Blondie Street. The rest of the Griswolds’s neighborhood is on a studio back lot as well. And if the home of their snooty neighbors, Todd and Margo, looks familiar, that’s because it’s where Roger Murtaugh (Danny Glover) and his family lived in Lethal Weapon.

3. John Hughes wasn’t a fan of sequels.

Though many of Hughes’s films have spawned sequels, the man himself was not a fan of retreads. “The only sequels I was involved in were under duress,” Hughes once stated in an interview. Though he’s credited as a writer on European Vacation, he said that was only because he had created the characters. “But the studio came to me and begged for another [Vacation movie], and I only agreed because I had a good story to base it on. But those movies have become little more than Chevy Chase vehicles at this stage. I didn't even know about Vegas Vacation until I read about it in the trades! Ever since it came out, people have been coming up to me with disappointed looks on their faces, asking ‘What were you thinking?’ ‘I had nothing to do with it! I swear!’”

4. It’s one of only two Christmas movies released in 1989.

Though the holiday season is usually packed with Christmas-themed movies, Christmas Vacation was one of only two that were released in 1989. The other was John Hancock’s Prancer. Johnny Galecki, a.k.a. Rusty Griswold, starred in both.

5. Audrey is (miraculously) older than Rusty.

In both the original Vacation and European Vacation, Rusty is believed to be the older of the two Griswold children. In Christmas Vacation, Rusty somehow morphs into Audrey’s younger brother.

6. The film has ties to It’s A Wonderful Life.

In addition to footage from the Frank Capra classic actually appearing in the film, Christmas Vacation has another fun tie to It’s a Wonderful Life: Frank Capra’s grandson, Frank Capra III, is Christmas Vacation’s assistant director.

7. The cast of Christmas Vacation was pretty impressive.

In addition to featuring future stars Johnny Galecki and Juliette Lewis (who scored a Best Supporting Actress Oscar nomination three years later for her role in Martin Scorsese's Cape Fear), star Beverly D’Angelo was most impressed with the older actors who came along for the Christmas Vacation ride. “I attribute that to Jeremiah Chechik and his direction in bringing in E.G. Marshall, Doris Roberts, and Diane Ladd,” she noted. “That was really a special cast.”

8. In a way, Stanley Kubrick is to thank for Christmas Vacation.

Christmas Vacation marked the directorial debut of Jeremiah Chechik, who began his career as a fashion photographer for Vogue then moved into commercial directing. “I had made these commercials that became quite iconic here in the U.S.,” Chechik told Den of Geek! in 2011. “They were very dark and sexy and sort of a little bit ahead of their time in terms of style. And what happened was they gained the notice of [Stanley] Kubrick, who had mentioned them as his favorite American filmmaking, ironically, in a New York Times article.” It didn’t take long for Chechik’s phone to start ringing and for studios to start sending him scripts. “And the script that really piqued my interest was Christmas Vacation," he said. "And the reason is I had never done any comedy—ever.”

9. Director Jeremiah Chechik had never seen a Vacation movie.

“I hadn't seen the first two [Vacation movies], and so I wasn't really influenced by anything other than the fact that it was a big—at the time—their big Christmas movie, and comedy,” Chechik said. “And I just felt if I could crack this maybe there's a whole other world of filmmaking for me.” Following Christmas Vacation, Chechik directed Benny & Joon, Diabolique, and The Avengers (no, not the Marvel one) plus episodes of The Bronx is Burning, Gossip Girl, Chuck, and Burn Notice.

10. The movie had a huge budget, particularly for a comedy.

A $27 million budget, to be exact. Which was particularly high considering that the film had no special effects a la Ghostbusters (which was made for $30 million). But it had no trouble making its budget back; the film’s final domestic gross was $71,319,526.

11. Roger Ebert did not love the film.

Though it has become a bona fide holiday classic, not everyone was a fan of Christmas Vacation. In his two-star review of the film, Roger Ebert described the movie as “curious in how close it comes to delivering on its material: Sequence after sequence seems to contain all the necessary material, to be well on the way toward a payoff, and then it somehow doesn't work.”

12. It’s the only sequel in the Vacation franchise to have its own sequel.

But don’t be disappointed if you didn’t know that. Or haven’t seen it. The 2003 film, National Lampoon’s Christmas Vacation 2: Cousin Eddie’s Island Adventure, was made for television. It finds Randy Quaid and Miriam Flynn (as Eddie and Catherine) stranded on an island in the South Pacific for the holidays. Yes, really. It currently holds an 11 percent approval rating on Rotten Tomatoes.

13. Audrey is the only Griswold to appear in Christmas Vacation 2.

Dana Barron, who played Audrey in the original Vacation, reprised her role for the Christmas Vacation sequel. Eric Idle, who appeared in European Vacation, also makes an appearance, playing “English Victim.”

14. Cousin Eddie is Randy Quaid’s best-known character.

At least it’s the role that gets him the most recognition. In a 1989 interview with the Los Angeles Times, Quaid admitted that he was amazed by the impact the character made. “People still come up to me and quote lines from that part. I get a lot of recognition from that role—probably as much, if not more, than any other.”

15. Cousin Eddie is based on a real guy.

Quaid borrowed many of Cousin Eddie’s mannerisms from a guy he knew growing up in Texas, most notably his tendency toward tongue-clicking. But Eddie’s sweater/Dickie combo? That was an idea from Quaid’s wife.

16. You can buy your own Dickie.

National Lampoon’s Christmas Vacation Collectibles is a website dedicated to all things Christmas Vacation (obviously). Among the many fun items are Cousin Eddie wardrobe staples, moose mugs, and punch bowls.

17. Eddie’s son, rocky, doesn’t speak in the film.

Nope, not a word.

18. Aunt Bethany is Betty Boop.

Christmas Vacation marked the final film of Mae Questel, who began her career as the voice of Betty Boop in 1931. She passed away at the age of 89 in January of 1998.

19. Cousin Catherine has a Looney Tunes connection.

Turns out Aunt Bethany isn’t the only voice actress in the family. Miriam Flynn, who played Eddie’s adoring wife in four Vacation pictures, voiced Taz’s mother on the animated Warner Bros. series Taz-Mania. She’s also lent her vocal talents to The Land Before Time franchise and she portrayed Maa the elderly sheep in Babe.

20. Bethany and Louis’s entrance made the earth move.

At the same time the production filmed the arrival of Uncle Louis and Aunt Bethany at the Griswold home, a minor earthquake struck. The camera shakes slightly as a result of it as Bethany walks through the front door.

21. Christmas Vacation went straight to video in England.

Though the movie is a popular holiday film in the UK, it was never actually shown in theaters there. Instead, it went straight to home video.

22. You won’t hear “Holiday Road” in Christmas Vacation.

Christmas Vacation is the only movie in the series that doesn’t feature Lindsey Buckingham’s song, “Holiday Road.” Instead, a new song—the aptly titled “Christmas Vacation”—was written for the film by married songwriting duo Barry Mann and Cynthia Weil. A cover of the song appears on the 2007 Disney Channel Holiday album.

23. Randy Quaid is the third cousin of Gene Autry.

Which may just sound like a random fact. But at the end of the film, when the police raid the Griswold home, the version of “Here Comes Santa Claus” being used is Autry’s.

24. Ellen Griswold lied to the cops.

In the same scene, Ellen Griswold apologizes to Mrs. Shirley—the wife of Clark’s boss/Eddie’s kidnapping victim—assuring her that “This is our family's first kidnapping,” when, in fact, it is their second. At least the second that we know of: In the first Vacation film, the Griswolds force Lasky, the security guard at Wally World (played by John Candy), to open the park for them.

25. Chevy Chase, Beverly D’angelo, and Juliette Lewis reunited In 2012.

The trio got together to film a series of Old Navy commercials for the holiday season. Though Johnny Galecki wasn’t there, two previous Rustys—Anthony Michael Hall and Jason Lively—were. As was Dana Barron.

26. Johnny Galecki received an award from Chevy Chase.

In a 2012 interview, The Sydney Morning Herald asked Johnny Galecki whether he had kept in touch with Chevy Chase since the film. He admitted that “the only time I’ve seen him since that movie, which was 21 years ago I think, is when he presented us with our People’s Choice Award, so that was really neat. If you’re going to run into Chevy again it may as well be as he’s giving you an award.”

27. Chevy Chase and Beverly D'angelo were anxious to see another Vacation movie happen.

On July 29, 2015, the latest film in the Vacation franchise—simply titled Vacation—made its debut. And it couldn't have happened soon enough for Chase and D'Angelo. In 2011, Chase told Ain’t It Cool News that “I just got off the phone with Beverly D’Angelo. We are trying to work up a new Vacation and apparently Warner’s is working on one with grandchildren, but the one that Bev and I want … You know, we are just trying to think of ideas, because she is very funny and very brilliant, so when you get her in a writing mood and me in writing mood, it’s good, but it’s very hard to get the time.”

28. The studio won that one.

Chase and D’Angelo may have had their own ideas, but the studio moved ahead with that whole “one with grandchildren” thing. Written and directed by John Francis Daley (Sam from Freaks and Geeks) and Jonathan M. Goldstein (who wrote Horrible Bosses), Vacation featured a grown-up Rusty (played by The Office's Ed Helms) taking his own family on a road trip.

29. Beverly D’Angelo improvised a risque sight gag for the SWAT team segment.

Take a good look at the Griswold clan after one of the SWAT leaders yells, “Freeze!” During the mayhem, Ellen plants her right hand firmly on Clark’s crotch—and keeps it there. “I did that spur of the moment and told Chevy, just to see if anyone on set noticed,” D’Angelo told Rolling Stone. “But we did a couple takes and no one mentioned it.”

30. A number of scenes were filmed in Breckenridge, Colorado.

It’s not like the Rockies are within driving distance of the Griswolds’s Chicago residence, but that’s where Clark and the family go hunting for the “perfect Christmas tree” early in the movie. Most of that sequence was shot on location in the greater Breckenridge, Colorado area. Also, the hillside where Clark and the kids go sledding is a famous Breckenridge ski slope.

31. Mr. Shirley (a.k.a. Clark’s boss) is Bill Murray’s brother.

Brian Doyle-Murray and National Lampoon go way back. Not only did Doyle-Murray appear in two of the Vacation movies (look for him in the original flick’s Kamp Komfort scene), but he also made frequent appearances on The National Lampoon Radio Hour. And oh yeah—he’s Bill Murray’s older brother.

32. Johnny Galecki got a big scene cut from the movie—and he still regrets it.

Clark and Rusty share a heartfelt chat in both of the previous Vacation movies. Yet, in Christmas Vacation, they don’t really get one. A dialogue-driven “man-to-man” scene written by John Hughes never made it into the final shooting script. On the set, Chase wanted to film that scene anyway, but Johnny Galecki felt differently. “They asked what I thought and I said, ‘I don’t think there’s any point,’” Galecki told Rolling Stone in 2014. “I literally talked myself out of what could have been a classic scene with Chevy Chase. Now ... I realize the error of my ways. I still kick myself in the ass for this every day.”

33. Eddie and Ellen kept a running joke alive.

When these two first meet in the original Vacation, Christmas Vacation, and again in Vegas Vacation, Eddie tries to kiss Ellen on the lips. He goes 0-for-3.

34. On-set, Chevy Chase became a comedy tutor.

In a 2018 Variety interview, Galecki said that while the script required Rusty to do “some heavy comedic lifting,” his own sense of timing “wasn’t on point.” “Chevy would help me out, especially with the timing, and tell me some ad-libs to say,” Galecki recalled. Sometimes, during lunch breaks, Chase used to bring his co-star to the sets of Harlem Nights and Ghostbusters 2. “Here I am at 13 being introduced to Redd Foxx and Eddie Murphy and Dan Aykroyd and Bill Murray and Richard Pryor and all these incredible, incredible comedic icons,” says Galecki. “[Chase] didn’t have to do that, and it’s still very touching to me.”

35. You can buy a Clark Griswold Chicago Blackhawks jersey.

Chicago hadn’t won the Stanley Cup since 1961 when Christmas Vacation came out in 1989, but that didn’t stop Clark and Rusty from rocking some Blackhawks merch on-screen. Amazon now offers a replica of the home jersey that Chevy wore in the film; the name “Griswold” is sewn onto the garment’s backside.

36. Chevy Chase suffered a hand injury.

The accident happened on-screen while Clark was demolishing Santa’s sled after his (second) failed attempt to get the X-mas lights up and running. Old St. Nick got his revenge: Chase broke his pinky during the assault. Since the cameras were rolling, he couldn’t stop without ruining the take. “I had to keep kicking because it hurt so much,” said Chase in 2015.

37. All the presents on Mr. Shirley’s office desk—including Clark’s—look exactly the same.

Sure they’re wrapped differently, but size- and shape-wise, the gifts are identical. Go re-watch the movie if you don’t believe us.

38. To help Chase nail that expletive-filled tirade, his fellow actors wore cue cards.

As D’Angelo explained in a 2015 conversation with The Dinner Party Download, “this particular scene ... was blocked in a way that would allow each of us to have around our necks a piece of rope that was attached to a big cue card. The rant was divided into sections so that he could go all the way through from the beginning to the end without a chance of forgetting his lines ... If you watch it, you can see him. His eyes go from character to character as he’s going on in the speech because we’ve got the lines there.”

39. The film's producer made a hidden cameo.

Matty Simmons, who produced the movie, is on the cover of the magazine that gets stuck to Clark’s hand while he talks vacation plans with Ellen. By the way, Chevy Chase reportedly kept the pajamas he wore in that same bedroom scene until (at least) 2015.

40. Ruby Sue took a fancy to her “cousin.”

You don’t see much of actress Ellen Hamilton Latzen these days; she’s mostly remembered for her role in Fatal Attraction and her signature performance as Eddie’s daughter in Christmas Vacation. In a chat with Bill Bradley of HuffPo, she spoke fondly of the National Lampoon classic’s family dinner scene. “I remember sitting at the end of the table that was the kids section with Cody [Burger] and Juliette [Lewis] and Johnny Galecki, who I had a massive crush on—a huge crush on Johnny Galecki—and I remember having little marshmallow fights with him and always trying to get his attention,” Latzen said.

41. Cleveland-area fans can visit a genuine “Griswold House” each Christmas.

Each year, Christmas Vacation superfan Greg Osterland and his family adorn their Wadsworth, Ohio residence with an exact duplicate of Clark’s over-the-top lighting arrangement. (And this holiday season, they’re adding a replica of Cousin Eddie’s banged-up RV.) Visitors are encouraged to make donations to the Great Strides Cystic Fibrosis Foundation.