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)
Visible crew/equipment: After Lucifer talks to God and doesn't know what is happening and Saint Peter comes to escort him out they get into a discussion why he failed the entrance examination, you can see a reflection in glass between the camera and Lucifer and a man who does not appear to be St. Peter. (Maybe director Stanley Donen?) (01:39:25)
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.
Revealing mistake: Despite the best efforts, you can tell the fabled white rhino is just a prop on wheels.
Factual error: When Jeremy and Jack climb the beanstalk and arrive on the clouds, it starts to rain. Where is the rain coming from?