We’ve all been there: imprisoned in a hotel room for 15 years without explanation, then set free and given a chance to find our tormenters. This scenario was first explored in Park Chan-wook’s disturbingly beautiful Oldboy, complete with a masterful single-take 50-against-one fight in a hallway. (The less said about Spike Lee’s 2013 remake, the better.) You might already know a lot about the violent Korean vengeance thriller, but here are 11 more facts to really hammer it home.

1. THE LEAD ACTOR ONCE FELL ASLEEP DURING FILMING.

If you think watching Oldboy is exhausting, imagine what it was like making it. The work was especially taxing on Choi Min-sik, who’s in every scene, often fighting with people or eating a live octopus. The hard work caught up with him while filming the penthouse sequence, when, at some point when he was lying on the ground (in character), he simply dozed off between takes. The crew had to gently awaken him when it was time for the cameras to roll again.

2. THE EPILOGUE WAS SHOT IN NEW ZEALAND BECAUSE THAT’S WHERE THE NEAREST SNOW WAS.

Chan-wook wanted it to be obvious that the epilogue was taking place after some time had passed (though he wanted it to be ambiguous whether it was weeks, months, or years). A change of seasons is the simplest way to show that visually; problem was, there was no snow in South Korea at the time. So the director and his crew headed to the Southern Hemisphere, where New Zealand had plenty of the stuff. 

3. THE EPILOGUE WAS SHOT WITH BORROWED CAMERAS AND COSTUMES BECAUSE THE AIRLINE LOST THEIR LUGGAGE.

One more reason not to shoot on location: When Chan-wook and his crew flew to New Zealand, their luggage—which included their cameras and costumes—didn’t arrive with them. The production had to scramble to rent cameras locally (not too hard), and to quickly produce costumes that could stand in for the ones they’d painstakingly crafted back in Korea (this was a bit trickier).

4. THE ANTS IN THE ARM WERE COMPUTER-GENERATED—AND SO WAS THE ARM.

There’s a lot of CGI in Oldboy, most of it subtle. (The knife sticking out of Dae-su’s back for much of the hallway hammer fight, for example.) One of the more obvious uses is in the scene where Dae-su hallucinates ants crawling out of his arm and then swarming his face. Not only were the ants fake, so was the arm. The digital whizzes determined that it would be easier to create the effect if both components, ants and arm, were CG, rather than one of them being a live-action image. But when the left hand comes into the frame and flicks an ant away? That hand is real.

5. YES, CHOI MIN-SIK REALLY ATE A LIVE OCTOPUS.

The scene where Dae-su hungrily devours a live octopus would seem to be a good occasion for digital trickery, especially considering the actor, Choi Min-sik, is a Buddhist and a vegetarian. But nope. He really did it—four times, in fact, as that’s how many takes it took. Chan-wook said that “before every take, [Choi] would pray to the octopus offering it his apology.” Whether the octopuses (yes, that’s the right word) accepted the preemptive apologies is not known.

6. IT ALMOST WON THE TOP PRIZE AT CANNES, BUT MICHAEL MOORE GOT IN THE WAY.

Quentin Tarantino was jury president that year (2004), and he was, unsurprisingly, an enthusiastic supporter of Oldboy. It ended up winning the Grand Prix, essentially the second-place prize after the Palme d’Or, which went to Michael Moore’s documentary Fahrenheit 9/11. Rumors circulated that Oldboy lost the top prize by a single vote, though the Cannes jury would never confirm it.

7. THERE WAS A PLAGIARIZED INDIAN VERSION.

One popular pastime within India’s amazingly prolific Bollywood film industry is to remake foreign movies without asking permission. Sometimes they are mere rip-offs and imitations; sometimes it’s all-out theft. Zinda, released in 2006, was more of the latter, though nobody ever got around to suing the filmmakers. 

8. YOO JI-TAE WAS GOOD AT YOGA, BUT NOT THAT GOOD.

The scene where Dae-su’s rich, enigmatic tormenter, Lee Woo-jin, does yoga in his penthouse apartment cheated a little. The actor, Yoo Ji-tae, was a lithe 26-year-old at the time, but the extreme Locust pose—where he lies on his stomach and bends his back, lifting his legs high up in the air—was too much for him. Park used wires to make Woo-jin look almost supernaturally flexible.

9. THE MAIN CHARACTER WAS NAMED AFTER OEDIPUS.

Chan-wook said he chose the name Oh Dae-su “to remind the viewer of Oedipus. I was thinking of Greek myth or the classics.” If you remember your classics, you’ll recall that Sophocles’ tragedy Oedipus Rex concerns a man who inadvertently marries his own mother (whoops!).

10. IT’S BASED ON A JAPANESE MANGA SERIES.

Minus the incest. No, that horrifying twist—where Woo-jin manipulates Dae-su into sleeping with his own daughter—was all Chan-wook’s idea. The original is also considerably less violent than Chan-wook’s film, and the villain has different reasons for afflicting the hero.

11. DESPITE ALL OF ITS SEEMING ADVANTAGES, THE AMERICAN REMAKE MADE EVEN LESS MONEY THAN THE ORIGINAL.

Chan-wook’s film made just $700,000 in its tiny U.S. release, but a healthy $14.2 million elsewhere in the world. (In its native South Korea, it was the fifth top-grossing film of 2003.) The 2013 American remake—with its big-name director (Spike Lee) and A-list cast (including Josh Brolin and Samuel L. Jackson), not to mention the advantage of being in English—flopped, making just $4.8 million worldwide. Revenge is sweet (except in Oldboy)!

Additional sources:
Special features and commentary on the U.K. Blu-ray release.