Revealing mistake: In the beginning, the harem teacher and his pupils read the story (which becomes the movie) from the book Arabian Nights. The huge book propped up in front of the old man, though, is only an empty cover with no pages at all.
Revealing mistake: When Orville and Jeff are in jail, the superimposed background bleeds through onto the jail guard's caftan. (01:09:15)
Revealing mistake: Inventor Dr.Tobel is shown with his bomb sight. Later in the film we see the same equipment, only this time it is Sherlock Holmes' ultraviolet light apparatus. (00:22:05 - 00:45:30)