I haven't seen the movie in quite a while but i remember this slip up pretty well. It's at the very beginning when Indy and that guy are escaping the booby-trapped cave. The guy has just back-stabbed Indy and he has to get over the big hole in the floor while the whole place is shaking. It shows a shot of the stone door which is shutting downwards and Indy is still trying to get across. The door is almost shut now and you're wondering how Indy will get under it without being squashed when the magic of movies brings the door up to mid-way position in the next shot and he escapes!