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: 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: 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.