Continuity mistake: After Jack strangles the police officer there are 3 guys by the door - he knocks down one of the them but in the next shot there is just one man left.
The Invisible Man (1933)
1 continuity mistake - chronological order
Directed by: James Whale
Starring: Claude Rains, Henry Travers, Gloria Stuart, William Harrigan
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: We'll begin with a reign of terror, a few murders here and there, murders of great men, murders of little men - well, just to show we make no distinction. I might even wreck a train or two... just these fingers around a signalman's throat, that's all.
Trivia: A purely technical error with all "invisible man/woman/boy" movies is that the eye works by interacting with light incident upon the retina. The Invisible Man is made so by being rendered transparent to visible light. This means that his eyes no longer interact with light - so he ought to be completely blind. (However, a healthy suspension of disbelief makes for a great story.).