- Big-Lipped Alligator Moment: In the book, Nightmare Fetishist Gilbert Wynant asks Nick Charles about various criminal and insane behaviors, like cannibalism. Nick points Gil to the story of Alferd Packer — and Hammett inserts an in-story reference article on Packer that runs roughly six pages (in a mass-market paperback edition). It's never brought up again.
- Harsher in Hindsight: The book and film provided the code name for a nuclear bomb design in the Manhattan Project. "Fat Man" and "Little Boy" bombs, which went on to be dropped on Japan, were named according to the convention set by Thin Man.
- I Am Not Shazam: Nick Charles is not the Thin Man. However, some of the later sequels' titles gave in and used it like he was.
- Retroactive Recognition:
- Jimmy Stewart in After
- Shadow was Donna Reed's second film.
- Dean Stockwell plays Nick Jr. in Song, near the start of one of the longest acting careers in film history.
- Values Dissonance: To a modern eye Nick comes off as a hopeless alcoholic.
- Though he actually quits drinking by movie five. Sobriety doesn't change his behavior very much.
- There's about as much joking about threatened spousal abuse as The Honeymooners. Plus, in the first film Nick actually does hit Nora in the face (to get her out of the way of a bullet, but still).
- In the book, Guild uses the N-word when referring to a mugger who had killed another man. The slur is casually used once in the book's dialogue, but would be completely unacceptable in today's world.
YMMV / The Thin Man