- Creator-Chosen Casting: James Whale cast Claude Rains, whom he met at a London performance of The Insect Play in 1923.
- Darkhorse Casting: Claude Rains was a stage actor in New York and London. Universal discouraged James Whale from casting him, not wanting an unknown actor in the lead.
- Hostility on the Set: Gloria Stuart didn't enjoy working opposite Claude Rains, as he constantly upstaged her. When they had scenes together, he kept backing her into the scenery and hampering her chances to perform. James Whale had to keep everything on an even keel by reminding him that he had to share scenes with her.
- Star-Making Role: For Claude Rains.
- What Could Have Been: Boris Karloff was the original choice to play Griffin but decided not to take the role, partly because his face would only be on-screen for a few moments (when Griffin dies at the end), but also because Universal president Carl Laemmle wanted him to take a pay cut.
Trivia / The Invisible Man (1933)