Continuity mistake: In the dream scene where Larry writes on the blackboard in front of the student audience, when Larry writes on the blackboard he writes the wrong formula "delta p = square root of <p>^2 - <p>^2". The bell rings, the students leave and you see Larry again in a close-up and above his shoulder you see the the first 2-squared moves from outside the bracket into the bracket. (01:06:35)
Other mistake: Because of the way it works when making a mold, the engraving on the man's teeth would barely have been captured, yet they showed up sharp and clear when the mold was removed.
Factual error: Although the film is set in 1967, the school buses have folding stop signs on the side, which weren't available until the late 70s.
Continuity mistake: Nearly one hour into the movie Larry meets the second rabbi. While they talk that rabbi drinks a cup of tea with the teabag in it and the label hanging down. That label first hangs down at the right side of the cup and then at the left side. Seconds later it has jumped to the saucer on the desk and then jumps back into the cup with the label hanging on the left side again. (00:56:30)