19 Surprising Facts About 'The Dark Knight'

Christopher Nolan didn’t set out to make sequels. As the director of hit thrillers like Memento and Insomnia, his personal style never seemed to mesh with the idea of helming a mega-franchise. After reenvisioning the Caped Crusader with 2005’s Batman Begins, though, Nolan couldn’t stop thinking about how his version of Batman would respond to the introduction of The Joker. The result was The Dark Knight, a hyper-real exploration of how chaos shakes up the mission of the righteous, complete with huge stars, incredible stunts, and an Oscar-winning performance by the late Heath Ledger. To revisit this landmark movie, which was released 15 years ago, here are some fascinating facts about The Dark Knight.

1. The Dark Knight has many comic book inspirations.

While it doesn’t adapt any one specific story to the screen, The Dark Knight did draw inspiration from several specific Batman stories in the pages of DC Comics. When researching and writing the film, Christopher Nolan and his brother, co-writer Jonathan Nolan, specifically went back to The Joker’s very first appearance in 1940’s Batman #1 in search of how best to introduce the character. Co-writer David S. Goyer, himself a DC Comics contributor, also cites the classic stories The Long Halloween, The Dark Knight Returns, and The Killing Joke as keys to his research, with elements from each making their way into the film.

2. The Joker also had diverse inspirations.

In addition to classic Joker stories like The Killing Joke, Nolan and star Heath Ledger drew on a diverse array of influences both in and out of comics to craft the film’s version of the Clown Prince of Crime. Before attempting to write the character, the Nolan brothers revisited Fritz Lang’s classic film The Testament of Dr. Mabuse as a study in how to write supervillains. Visually, Nolan also specifically cited the work of painter Francis Bacon as a touchstone for Joker’s distorted view of the world.

As for Ledger, he famously locked himself away in a hotel room for weeks, experimenting with voices and mannerisms until he developed something he was satisfied with. Among his inspirations: Sex Pistols icons Johnny Rotten and Sid Vicious and the anarchist character Alex from Stanley Kubrick’s classic film A Clockwork Orange.

3. Christopher Nolan was initially reluctant to make a sequel.

The Dark Knight was Christopher Nolan’s first sequel, and though Batman Begins ends with Gordon handing Batman the Joker card as a kind of setup for the next film, the director wasn’t exactly determined to return to Gotham City. Nolan and Goyer had ideas for how a trilogy of films would happen, of course, but after Batman Begins hit big, Nolan instead went off to make the magician drama The Prestige. Ultimately, the lure of telling a Joker story proved too enticing for Nolan to pass up, and he eventually re-teamed with Goyer to begin mapping out the story that would become The Dark Knight. 

“I didn’t have any intention of making a sequel to Batman Begins and I was quite surprised to find myself wanting to do it,” Nolan told Empire Magazine in 2009. “I just got caught up in the process of imagining how you would see a character like The Joker through the prism of what we did in the first film.”

4. Heath Ledger was the first choice to play The Joker.

Though other stars like Adrien Brody expressed an interest in playing the film’s key villain, Heath Ledger was the only name on Nolan’s wish list.

“When I heard he was interested in the Joker, there was never any doubt. You could just see it in his eyes,” Nolan told Newsweek. “People were a little baffled by the choice, it’s true, but I’ve never had such a simple decision as a director.” 

5. Yes, Ledger really did keep a Joker diary.

Because of the actor’s untimely death in January 2008, at the age of just 28, Ledger’s performance as The Joker has been somewhat mythologized by fans, so the idea that he kept a secret “Joker diary” while getting into character might sound apocryphal. In fact, Ledger really did make a diary while preparing to play the character. It included various clipped art (Alex from A Clockwork Orange figures heavily), stylized notes, and even lines from the script recopied in his own handwriting. In 2013, Ledger’s father Kim revealed the diary in a documentary, and noted that his son did immersive work like this for every role but “really took it up a notch” for The Joker.

6. Maggie Gyllenhaal wasn't the only actress considered for Rachel Dawes.

For the role of Bruce Wayne’s childhood friend and current Gotham City assistant district attorney Rachel Dawes, Nolan had to look for a replacement. Katie Holmes played the role in 2005’s Batman Begins, but opted out of the sequel ostensibly so she could act in the comedy Mad Money. So Nolan went in search of other actresses and ultimately decided on Maggie Gyllenhaal for the role. Gyllenhaal was the final choice, but she wasn’t the only one. Other actresses up for the role included Rachel McAdams and Emily Blunt.

7. Gyllenhaal accepted the role based on Nolan's presence alone.

For many actors, the prospect of starring in a sequel to a hit film is a major draw. For others, the prospect of finally being a part of a Batman film would do the trick. For Gyllenhaal, who stepped in as Rachel Dawes, there was only one key reason to say yes: Christopher Nolan.

“When Chris approached me about the film, it was almost incidental that it was about Batman,” Gyllenhaal said. “I was lured into becoming intrigued by the character through the process of making the movie. From the very beginning, Chris was so interesting and engaging—and so interested in me and my ideas about Rachel—that I wanted to be a part of it.”

8. Aaron Eckhart wasn't the only star considered for Harvey Dent.

Though The Dark Knight is unquestionably a Batman movie, Nolan and company didn’t consider the Caped Crusader to be the film’s main character.

“Bruce Wayne was the protagonist of the first film,” Goyer said, “but we decided early on that he would not be the protagonist of the second film—that, in fact, Harvey Dent would be.”

To that end, finding the right actor to play Gotham’s district attorney was crucial. Nolan ultimately chose Aaron Eckhart, who reminded him of Robert Redford, to play the part, but Eckhart wasn’t the only star considered. Other potential Harvey Dents included Matt Damon, Mark Ruffalo, and Ryan Phillippe.

9. Michael Caine didn't think the film would work ... until Ledger was cast.

Batman fans weren’t the only skeptics when it came to Nolan’s decision to deliver a new cinematic Joker. Michael Caine, who played Bruce Wayne’s loyal butler Alfred, was very apprehensive when  Nolan told him The Dark Knight’s villain would indeed be the Clown Prince of Crime, namely because Jack Nicholson’s performance as the character in 1989’s Batman still cast a very large shadow.

“You don’t try and top Jack,” Caine said.

When Nolan informed Caine that Ledger had been cast in the role, though, the film legend came around.

“I thought: ‘Now that’s the one guy that could do it!,’” Caine said. “My confidence came back. And then when I did this sequence with Heath, I knew we were in for some really good stuff.”

10. The Joker‘s scars were inspired by a real person.

Nolan deliberately resisted the idea of giving The Joker an origin story in the film, opting instead to portray him as a force of pure anarchy with no discernible motivation other than chaos. For this reason, the character’s scarred face—as opposed to the chemically-induced frozen grin given to the character’s previous movie incarnation—had no clear source. In fact, the character deliberately tells different stories to different characters to explain where the scars came from. As a result, prosthetics supervisor Conor O’Sullivan was driven to take inspiration for the scars from real life. So, he used an actual man on the street as a reference.

“I immediately thought of the punk and skinhead era and some unsavory characters I had come across during this time,” O’Sullivan recalled. “The terminology for this type of wound is a ‘Glasgow’ or ‘Chelsea smile.’ My references had to be real. A delivery of fruit machines was made to the estate near my workshop and the man delivering them had a ‘Chelsea smile.’ I plucked up the courage to ask him for a photo and he told me the story of how he had got his scars while being involved with ‘a dog fight;’ needless to say I didn't pursue the matter, but the photos proved to be very useful reference.”

11. Ledger licked his lips because of The Joker prosthetics.

One of the most identifiable characteristics of Ledger’s portrayal of The Joker is the way he almost constantly licks his lips inside and out, probing his scars with his tongue over and over again. It adds energy to the character as well as a certain menacing quality, but it apparently was not planned. According to dialect coach Gerry Grennell, who worked with Ledger on the film, that tic arose because the scar prosthetics—which extended into Ledger’s mouth—would loosen as he performed. So, he licked his lips repeatedly in an effort to keep them in place.

“The last thing that Heath wanted to do was go back and spend another 20 minutes or half hour trying to get the lips glued back again, so he licked his lips. A lot,” Grennell recalled. “And then slowly, that became a part of the character.”

12. The movie made IMAX history.

Though IMAX cameras are now being used to shoot entire feature films, at the time The Dark Knight was made, the format was primarily used for documentary films to showcase things like the wondrous detail of nature. Nolan had longed for years to bring the format to features, and opted to use the ultra-heavy, ultra-expensive cameras to film several major sequences in The Dark Knight. Most famously, the film’s prologue—featuring The Joker’s bank robbery—was filmed on IMAX and released early, in its entirety, as a teaser. Nolan has subsequently used the format for other films, including The Dark Knight Rises (2012), Interstellar (2014), Dunkirk (2017), and Tenet (2020).

13. The Joker freaked Caine out so much, he forgot his lines.

For the scene in which Bruce Wayne is hosting a fundraiser for Harvey Dent in his elegant Gotham City townhouse, Ledger and a group of Joker goons were meant to burst into the party via the elevator. Caine, as Alfred, was supposed to be there waiting to greet guests as the elevator doors opened, only to be frightened by the appearance of The Joker. Caine was there waiting, the elevator doors opened, and he was apparently so frightened by what he saw that any lines he was meant to deliver during the scene completely left his mind.

“I was waiting for Batman's guests, but (the Joker) had taken over the elevator with—he has seven dwarfs and ... oh! wait until you see them,” he said while promoting the film. “So, I'd never seen any of it and the elevator door opened and they came out and I forgot every bloody line. They frightened the bloody life out of me.”

14. The truck flipping sequence was done for real.

Embracing the hyperrealism of his version of Batman, Nolan opted to do many of The Dark Knight’s biggest stunts practically rather than relying on CGI. That includes arguably the biggest and most visually staggering stunt in the film: When Batman uses steel cables to flip The Joker’s 18-wheeler trailer over cab in the middle of a Gotham street. While another filmmaker might have opted to recreate the moment with computers or models, Nolan wanted to do it for real, on a real Chicago street. The task of pulling it off fell to special effects supervisor Chris Corbould, who ran tests in a more isolated area to ensure the flip wouldn’t harm any member of the crew or any neighboring buildings. With the tests successful, the production was primed to film the stunt … though Corbould still tried to talk Nolan into scaling it down.

“It was a funny thing—and this is always the way working with Chris—where he kept trying to talk me into a smaller vehicle,” Nolan said. “He said, ‘Can’t it be one of those SWAT vans, not an articulated truck?!’ I kind of went along with that for a while and we storyboarded it that way and kept talking about it. And I finally just went to him and said, ‘Chris, you can do this, you’re fine. It’s gotta be a huge truck, it’s gotta be a big 18-wheeler,’ and he went ‘Oh, all right,’ in that way he does, and he figured out a way to do it. Nobody had ever done it before and it was really a pretty amazing thing to watch.”

15. Christian Bale perched on skyscrapers himself as Batman.

One of the most beautiful shots in the film finds Batman, cape billowing around him, perched atop Chicago’s Sears Tower as he surveys his city. It’s a gorgeous image, but also one that easily could have been carried out by a stuntman so Bale didn’t have to take the risk. The star was having none of that. When he found out his stuntman Buster Reeves was preparing to perform the perch, Bale rushed to convince Nolan that he should be the one to stand 110 stories above Chicago for the helicopter shot. 

“It was important for me to do that shot,” Bale explained, “because I wanted to be able to say I did it.”

Bale also opted to perform a similar stunt in which Batman stands on a ledge of the IFC2 building in Hong Kong. By then, he was quite comfortable with the height.

16. Bale couldn't manage the Batpod.

One of the great visual hallmarks of Nolan’s Batman films is the introduction of the Batpod, The Dark Knight’s sleek motorcycle. While it may look like an oversized version of any other bike, the pod didn’t handle the same way, so a specially trained stunt driver was required. Jean-Pierre Goy was the man. He took to the vehicle immediately and trained for months to master the high-speed sequences required for the film. Bale, who was more than willing to volunteer to drive the Batpod, was ultimately only able to ride it when it was attached to camera rigs.

“Jean-Pierre was the only one who could master it,” Bale admitted. “Everybody else just fell off instantly.”

17. The film includes a small tribute to Ledger's daughter.

For the scene in which The Joker sneaks into a panicked Gotham hospital to see Harvey Dent, Ledger dressed up in a nurse’s uniform. If you look closely, you’ll see that the nurse’s name tag reads “Matilda.” Matilda is the name of Ledger’s daughter, who was born in 2005.

18. A sitting U.S. senator made a cameo.

When The Joker and his goons crash Bruce Wayne’s fundraising party, almost everyone in the room is intimidated into silence. One man, though, is not. He tells The Joker “we’re not intimidated by thugs,” and The Joker then grabs him and holds a knife to his mouth. That man is Patrick Leahy, the recently retired Democratic U.S. Senator from Vermont. A lifelong comic book fan, Leahy has appeared in five Batman films to date, including 2016’s Batman v Superman: Dawn of Justice, where he sat alongside actress Holly Hunter in a congressional hearing.

19. The mayor of a city called "Batman" sued the production.

Weird lawsuits surrounding major motion pictures are nothing new, but The Dark Knight inspired a particularly strange one. In late 2008, after the film had opened to rapturous critical acclaim and enormous box office success, Hüseyin Kalkan—the then-mayor of Batman, Turkey—sued Nolan and Warner Bros. for what he deemed a negative impact the film had caused on his city.

“There is only one Batman in the world. The American producers used the name of our city without informing us.”

Needless to say, given that Batman is still as popular as ever, the suit didn’t go anywhere.

Additional Source:
The Art and Making of The Dark Knight Trilogy, by Jody Duncan Jesser and Janine Pourroy

A version of this story ran in 2018; it has been updated for 2023.