Deliberate mistake: Father Merrin says, "It is He who commands you", and we hear and see the ceiling crack above his head. In the next shot we see the ceiling above him and they are no cracks in it, but four shots later we see the exact same spot and now cracks appear even though we hear no more cracking over-dubs after the first one. (01:49:15)
Deliberate mistake: In the scene where Bond and Kananga are fighting underwater, Bond shoves the bullet into Kananga's mouth. Then, Kananga rises up and explodes. He explodes like a balloon, with not much blood at all.
Deliberate mistake: The Studebaker in which Carol is first riding bears the license number JPM 351, which interestingly enough, is not only the same license number that Steve's 58 Chevy has, but is also worn by the car Curt is sitting on when he first meets the Pharaohs. To top it off, the Edsel driven by Cindy Henderson has plates reading PRC 596, which are also used by a silver 57 Chevy and a red pickup.
Deliberate mistake: When Clint Eastwood rides into town the first time,one of the buildings has tarpaper on the outside and doesn't seem to be from the same era.This is the first and last time that building is in any shots.
Deliberate mistake: Throughout the movie we hear every animal (and insects/arachnids as is the case with Charlotte and her offspring) with one exception. Every time Charlotte catches her meals in her web we never hear the fly or other insect she is descending upon cry for help, or plead with her to be spared. This is deliberate due to this being a kid's film but still bears noticing as a mistake due to the fact that they are the only ones rendered mute for plot convenience.