When Raiders of the Lost Ark hit the theaters in 1981, it introduced us to the whip-cracking archaeologist Indiana Jones and kicked off one of the most popular film series of all time. The film was a major critical and popular success, earning the title of highest-grossing film of the year as well as a few Academy Awards. Its popularity remains strong today, and is often named as the best action-adventure in film history.

We love sharing facts about movie magic (like these 82 mind-blowing movie facts), so we’ve rounded up 19 surprising facts about the filming of Raiders of the Lost Ark. Next time you watch it, you’ll love it even more. Let’s get cracking!

1. The famous scene in which Indy shoots the show-off swordsman was improvised. Harrison Ford was sick with food poisoning at the time and was too ill to perform the stunt as planned, so he suggested just “shooting the sucker.”

2. In order to get maximum creepy-crawliness for the scene in which tarantulas are crawling on Satipo’s back, the crew added a single female tarantula. Before adding her, the male tarantulas just sat there.

3. R2D2 and C3PO make an appearance in the Well of Souls scene.

4. Indiana Jones’ name comes from Marcia Lucas’ dog, Indiana, who also served as the inspiration behind Chewbacca.

5. Indy’s hat is without a doubt one of the most iconic pieces of headwear in film history. The hat was bought at the famous Herbert Johnson hat shop in Saville Row, London.

6. Indy’s whip was crafted by the company David Morgan, who supplied over 30 bull whips of the 450 series, of various lengths, for the first three movies.

7. The exploding head at the end, which used meat and liver for extra gore, had originally earned the film an R rating. The filmmakers didn’t want that to happen. The solution? Add a few layers of fire in front.

8. Toht’s melting face, the source of nightmares for many, was created using a combo of gelatin, colored yarn for muscles and sinews, and alginate (the stuff dentists use your impressions). It was melted using propane space heaters over the course of 10 minutes, and sped up afterwards.

9. How do you create a realistic sound effect for body blows? Whack a pile of leather jackets with a baseball bat, of course.

10. The sound effects for the giant rolling boulder (which was made of fiberglass) were created by holding a mic near the tires of a Honda Civic as it coasted down a gravel embankment.

11. In order to create the infamous snake scene in the Well of Souls, the crew bought every snake they could find from pet shops in London and the surrounding area. It wasn’t nearly enough, so they supplemented by using legless lizards and cut pieces of hose.

12. The sound of the snakes writhing was created by sound designer Ben Burtt sticking his fingers into a cheese casserole.

13. The capuchin monkey was somewhat uncooperative in giving the Nazi salute that he had been trained to do before filming and the crew spent several days trying to get a good shot. They finally tried bribery – the scene you see in the film is the monkey reaching for grapes.

14. The stare-down between Indy and the cobra was filmed using a sheet of glass between them. It’s good that they did, because the cobra was in fact fairly angry and spit venom on the glass.

15. As if snakes aren’t creepy enough, the Well of Souls scenes were filmed in the Overlook Hotel from “The Shining.”

16. It’s hard to imagine anyone other than Harrison Ford as Indy, but other actors considered for the role included Nick Nolte, Steve Martin, Bill Murray, Tom Selleck, Chevy Chase, Tim Matheson, Nick Mancuso, Jeff Bridges, Peter Coyote, and Jack Nicholson.

17. Sallah was originally going to be played by Danny DeVito. He dropped out due to scheduling conflicts with Taxi.

18. The sound effects for the ghosts escaping the Ark were created by filtering the sounds of sea lions and dolphins through a vocoder.

19. Despite all of the creative sound effects used in the film, Indy’s whip-cracking was created by simply recording Harrison Ford and sound effects recordist Gary Summers practicing their bullwhip skills outdoors.

Still hungry for more? Check out the awesome animated video below to get your fix.

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