Revealing mistake: When the farmer is going to shoot the sign the bank put up, you can very well see the mark where the hole is going to appear.
Revealing mistake: In the scene where King Arthur expounds on the joy of his kingdom, he has a Band-Aid on the back of his neck. (00:21:00)
Revealing mistake: When Spencer Tracey backs his car into the hotrod at the ice cream stand, you can see the hotrod already has a sizable dent before the car makes contact, probably a result of a previous take.
Revealing mistake: The day after their first date Benjamin drives through the pouring rain to pick up Elaine. If you look closely out the side windows of the car you can see that it's produced by a rain machine, it's actually a beautiful day with the sun shining. (01:07:40)
Revealing mistake: When Dr Dolittle is talking to the parrot and it raises its left leg, you can see a piece of string running past Dolittle's head used to raise its leg.