Factual error: During the travel to Nepal, "Thailand" is written on the map. The country has had this name only since 1939. This film takes place in 1936, when Thailand was called Siam. (00:23:20)
Revealing mistake: When Belloq's head explodes, the actor has been visibly replaced by a dummy.
Revealing mistake: When Indy is fighting the big German at the base of the airplane, Indy reaches down and grabs a handful of sand to throw in his face. You can see the finger marks in the sand from a previous take.
Revealing mistake: During the truck chase scene, Indiana is thrown or forced over the front of the bonnet and almost run over. There is a wide camera shot, and while holding on to the front fender, Indiana can be seen sitting on a chair which is attached to the truck. (01:27:40)
Continuity mistake: After Indy replaces the idol for a bag filled with sand, the position of the bag changes between frames.
Continuity mistake: When Indy climbs onto the pontoon of the airplane from the lagoon in the opening sequence, he is obviously wet from swimming in the lagoon. However, in the next scene as he climbs further, his clothes are miraculously dry as observed by watching them blowing freely during take-off. (00:12:05)
Continuity mistake: When Indy and Brody meet at the University with the two government officials, a group of rolled maps or plans are placed on a podium horizontally. Halfway through the scene, they are all laying vertically.
Revealing mistake: When the Nazis are about to glow (and die), check the one on our left. His shirt is already unbuttoned right where the light will subsequently glow (which was a mere light bulb). A second later, he triggers a device clutched in his right hand (seemingly a switch) seconds before his chest lights up. (01:47:25)
Continuity mistake: In the submarine dock of Geheimhaven, Captain Mohler is a man with dark hair in his mid or late thirties. But during the procession, he seems to be much older, with grey hair.
Continuity mistake: The distance between Otto and the Nepalese changes between shots, just as Toht begins saying "Surely he told you..."
Continuity mistake: In the Bantu Wind, the right arm of the soldier standing next to where Indy is hiding changes its position twice during Katanga's and Dietrich's speech. (01:36:18)
Continuity mistake: In the first scene of the procession, the Nazis are walking in a straight line along a path. In the next shot, they are now going around a curve.
Continuity mistake: In Geheimhaven, Indy watches the submarine hidden behind some ropes. When Marion comes out of the submarine and the camera focuses on the back of Indy's head, the ropes disappear. (01:39:13)
Visible crew/equipment: As the bad guys are leaving the dig site for Cairo, there is a shot of the black vehicle (lead car) looking right at the driver. On the bottom of the shot is a shadow of film equipment that shouldn't be there. The shot lingers, so the shadow is very visible. (01:22:50)
Continuity mistake: When Marion arrives on the deck of the Bantu Wind, Dietrich turns to look at her. Katanga is in the background, behind the colonel. But, just before Marion hits Dietrich, Katanga appears on the opposite side from where he was and catches Marion. (01:36:00)
Continuity mistake: In the shot after Belloq's death, the generator and the rock Indy and Marion are on disappear.
Continuity mistake: While the Holy Fire is killing the soldiers, in a shot of two soldiers being hit by the light, the stone wall is missing in the background of the scene. (01:47:30)
Continuity mistake: As Dietrich and Gobler come into the tent, Toht's leather case can be seen already opened. In the next shot, the case is suddenly closed.
Continuity mistake: Over Belloq's left shoulder and behind Toht, a soldier stands next to a klieg with a machine gun. In the next shot, the soldier's gun has disappeared. (01:44:25)
Continuity mistake: During the procession, after Indy hides behind the box, Captain Mohler can be seen walking with the soldiers behind the Ark. In the next shot, he's walking in front of the Ark.
Answer: Indy and Marcus Brody believed that the Ark needed to be studied. They certainly didn't want to put it back where it was found. They believed that the U.S. government would find the best archaeologists, researchers, and scientists in the world to study the Ark. They are both upset that instead, the government has decided to simply lock the Ark away. This is why Indy says, "Fools. They don't know what they've got there," as he is leaving the building.
BaconIsMyBFF