Continuity mistake: The gold mask on Orellana's face changes angle between shots.
Continuity mistake: Spalko steps on a tree to free herself from the ants, 2 meters away from where a soldier is starting to be eaten. A frame later the soldier is gone, there's not even a small mound where his corpse could be.
Continuity mistake: When the group enters the final temple the skull falls into the water. Mutt picks it up, and there's a shot of Mac grabbing some gold. Then back to a wide angle and Mac is repeating the previous movement with a totally different hairstyle.
Continuity mistake: After Mutt points at the waterfall, Indy grabs the skull and Mutt leans on him to raise up, yet a frame later from a different angle his hands are away from Indy.
Continuity mistake: When the raft is about to fall through the second waterfall, there's a huge rock to the left which disappears in the wide angle.
Continuity mistake: When Indy removes Orellana's golden mask, the light changes abruptly from very shiny to obscure and mysterious.
Continuity mistake: During the ant scene, the branch that Indy uses to knock out the Russian wasn't there in the first place, it magically appears between shots.

Continuity mistake: After Mutt's bike knocks down the "Better red than dead" banner it falls sideways; yet when the chasing car arrives, the banner is magically up again, ready to fall horizontally on the car's windshield.
Audio problem: During the chase inside the campus, a car destroys some stone vases and a blonde woman cries in terror while running away, yet her mouth is not moving.
Continuity mistake: When Indy and Mutt's bike is about to exit the campus, a green car is passing by, which disappears in the immediate wide angle of the street.
Continuity mistake: When Mutt and Indy ride inside the arched door in the campus, a couple runs away, yet appears still there from the opposite angle.
Continuity mistake: When Indy and Mutt are about to enter the university, the guard is holding both gate doors almost closed. A frame later he's holding one completely opened.
Continuity mistake: When the Akator temple starts to move, the sand by the groups' feet keeps changing from sandy with a couple of rocks, to filled with weeds and leaves, and back to sandy.
Continuity mistake: Inside the waterfall temple, the group walks by a room (with a passage on each side and a double entrance with steps in the middle) where natives appear and columns and walls fall off. The angle changes to a seemingly new room, but it's obviously the same place, with the camera angle slightly turned to the right. All the previous people are magically gone, the debris has disappeared, and natives are coming out of different places. Really odd editing. (01:30:35)
Continuity mistake: Mutt says, "We have to cross the waterfall," and extends her left hand. From the opposite angle, a frame later, he is extending the right arm.
Continuity mistake: When the Russians arrive at the barrier the sky is either sun setting, bright and sunny, or cloudy, depending on the angle.
Continuity mistake: When Indy finds out that Mac has betrayed him, Mac is standing half a meter away. Right after, from a different angle, he is 10 centimeters away, with the tip of his rifle touching Indy. And right away, from yet another angle, the gun is on top of Indy's shoulder.
Continuity mistake: When Mutt is pulling Indy out of the quicksand both are inches away from each other. A frame later Mutt is meters away in a different position, as if he had fallen backwards.
Continuity mistake: Indy's car crashes face to face against Mac's, destroying its front. When Indy runs away there's a view of the car and the damages are minor.
Continuity mistake: After Mutt falls from the ladder in the graveyard, a native jumps from above to attack him. Indy is already on the right side of the scene, walking out, but when the angle changes he is standing on the left side, very close to Mutt.
Chosen answer: Because the film had a global release date, and premiered the same day in every country in the world. Obviously, the studio felt this was the best day to do it.
Twotall