Other mistake: At the end when the naked but invisible hero runs from the police but is given away by his footprints in the snow, the footprints are of shoes, not bare feet.
The Invisible Man (1933)
1 other mistake - chronological order
Directed by: James Whale
Starring: Claude Rains, Henry Travers, Gloria Stuart, William Harrigan
Revealing mistake: When Jack steals the bike he's supposedly riding it but you can see a rail on the ground.
The Invisible Man: And if you try and escape by the window, I shall follow you, and no-one in the world can save you.
Trivia: Claude Rains' real face is only visible for about 20 seconds in the last scene of the film.