The famous scene in which Indy shoots a marauding and flamboyant swordsman was not in the original script. Harrison Ford was supposed to use his whip to get the sword out of his attacker's hands, but the food poisoning he and the rest of the crew had gotten made him too sick to perform the stunt. After several unsuccessful tries, Ford suggested "shooting the sucker." Steven Spielberg immediately took him up on the idea, and the scene was successfully filmed.
When Brody first goes to Indy's house to discuss the mission, Jones is dressed the way he is because he is entertaining a young woman in his bedroom. The script originally planned to show her before moving to the next scene, to give Indy a more worldly persona (like James Bond). However, her appearance was cut, as Steven Spielberg thought that being a playboy did not fit Indy's character. (This also helps explain why several of the co-eds fawn over Jones and why one girl wrote "love you" on her eyelids).
The out-of-control airplane actually ran over Harrison Ford's knee, tearing a ligament in his left leg. Lucky for him, the heat had turned the rubber tire's soft, so it did not crush the bone. Rather than submit to Tunisian health care, Ford had his knee wrapped in ice and carried on.
Steven Spielberg has said that he considers it the most perfect film of the series. He never wanted to modify it or change anything about it.
During filming in Tunisia, nearly everyone in the cast and crew got sick except director Steven Spielberg. It is thought that he avoided illness by eating only the food he'd brought with him: a lot of cans of Spaghetti-O's.
Frank Marshall: Pilot of the flying wing. All the stuntmen were sick on the day that Marion hits the pilot of the Flying Wing over the head, so producer Frank Marshall agreed to do it. Unfortunately for him, the shot took three days, and a lot of it involved him sitting in a cockpit that was in excess of one hundred degrees.
Terry Leonard: The stuntman who appears as the German truck driver also performed numerous stunts as Indiana, including jumping from the horse to the truck and sliding under the truck.
Dennis Muren: Appears as a Nazi spy who is tracking Indiana Jones on the airplane. Only his eyes can be seen, though, as most of his face is hidden behind the magazine he's reading, which is Life volume 1 number 2 (November 30, 1936), which has pages 42-43 dedicated to the water color paintings of Adolf Hitler.
Glenn Randall Jr.: The stunt coordinator appears as the mechanic with the monkey wrench at the flying wing.