Continuity mistake: When the white robed men ambush the Nazis just after they blow up Salah's car, there's a shot over a Nazi's shoulder as he fires at one of the white robed guys running up a hill. The Nazi's machine gun is held straight out and doesn't move but the dust that flies from the squibs suggest that he fired as he moved the gun right to left which he did not do. The odd thing is that AFTER the squibs go off, the Nazi turns his gun to the left. (01:25:55)
Factual error: When Hitler signs the Grail Diary, in the screen and VHS release he signs Adolph, not Adolf. This mistake was corrected in the DVD release. (01:07:35)
Continuity mistake: In the beginning where Indy is young, he fights some guys on that zoo train. When he's on the crate with the rhino in it, the background changes in each shot. Once there are trees behind and a split of a second later there are rocks, once there's a cliff and once a plain, and it all changes in splits of seconds as they change shots. (00:07:25)
Continuity mistake: When the Nazi Colonel discovers Henry Jones sen. aboard the zeppelin, Indy asks him for his flight ticket. In the first shot, Indy is standing right beside the colonel (the camera is behind the colonel and Indy comes in from the right), in the subsequent shot, Indy is standing behind the colonel.
Continuity mistake: At the airport, someone is reading a newspaper. Instead of the year 1938, the date of the newspaper is 1918 (a guess: I think this mistake happened because the art director wrote the date in a rush, stretching the "3" in a way it seemed a "1" when the people of "atrezzo" saw it).
Visible crew/equipment: When Indiana and the Protector of the Grail are fighting in the boat that is about to be chewed up by the giant screw/propeller, when the angle changes to the top point of view, you can see the rope pulling the front of the boat around to position the rear for destruction... (00:39:10)
Continuity mistake: When the tank is about to go over the cliff you can see that there is no one sticking out of it, but in the next shot, Vogel can be seen sticking out and yelling.