Continuity mistake: In the map room, Indy brushes the sand off of a stone, leaving a clean horizontal trail. A frame later, in the close-up, the upper left part above the trail is suddenly clean.
Continuity mistake: When Belloq traps Indy in the Well of Souls the sky keeps swapping between a dim yellow dawn sky, and a brilliant morning blue sky.
Continuity mistake: While Indy descends the Well of Souls the glowing logs underneath keep changing positions.
Continuity mistake: In the bar, the Nazi plays with the fireplace and threatens Marion, who takes a cigarette to her lips. A frame later, her hand is in a totally different position.
Continuity mistake: After the guy with the patch and the monkey greets the Nazis, Marion and Indy are seen walking through town, passing by an arched door. A frame later, from a different angle, they are passing by again and the amount of people around has increased.
Other mistake: The Angel of Death attacks the altar and Toht and Dietrich scream because of its revelation, but Belloq, for some reason, doesn't seem to see it. Just before the fire column rises, he's still calm. (01:47:10)
Suggested correction: If you don't know the reason, perhaps you should ask a question instead of assuming it is a mistake. Belloq studied the ark and probably better predicted what might come out of the ark. He is also looking directly into the ark and is mesmerized by what he is seeing, until eventually he does scream before his head explodes. The other two are terrified at seeing the apparitions.
Actually, it's pretty impossible that Belloq studied the Ark. If he knew what would come out of it, he literally committed suicide by opening and watching the Ark open, which doesn't make sense. He believed during the whole movie that the Ark contained the Ten Commandments tablets, not some kind of ghastly things.
He didn't know what would come out, but it doesn't mean that he, like Indy, expected just 2 stone tablets. He expected power, for him mostly.
Continuity mistake: In front of the idol, Indy shows Satipo the trap on the floor. Satipo's head position is different in all 3 shots in barely 2 seconds: First he's looking downwards, then straight, then his head is turned sideways, and then back to straight. (00:08:20)
Continuity mistake: The amount of moss behind the idol increases between shots.
Continuity mistake: Arnold holds a hot stick of metal to Marion's face in her bar, threatening her. In the opposite angle, the metal is nowhere to be seen when it should be right next to her face. Cut back to the other angle and we see it again.
Suggested correction: This entry is incorrect; the poker is always on screen, it never disappears.
Continuity mistake: In the marketplace standoff between Indy and his would-be attacker, in shots from behind Indy, he's facing one way, but in frontwards shots, he's facing a different way and when it cuts back to behind him, he's facing the other way again.