Actor-Inspired Element: The part where Susan's dress rips at the club was suggested by Cary Grant. He had got his pants zipper caught in another woman's dress and had to instinctively follow her as a result.
Creator Backlash: Howard Hawks says he regretted making everyone in the cast crazy, wishing there had been a straight man or two to keep things grounded. Averted with the two stars though, as they loved working on the film.
Fatal Method Acting: Narrowly averted. Katherine Hepburn was standing right in front of the leopard, wearing a skirt lined with little metal pieces to make it swing prettily. She made a sudden turn and the leopard lunged for her back. Only the trainer's whip saved her.
Missing Trailer Scene: The trailer is actually made up of a lot of unused takes of existing scenes in the movie.
Reality Subtext: The attitude of the two leads towards the leopard is reflected in their characters. Katherine Hepburn was more fearless around it, while Cary Grant was wary of it - to the point where doubles and stand-ins had to be used in a lot of scenes.
Science Marches On: The clavicle in question comes from a brontosaurus, which, even at the time, was recognized by the scientific community as Apatosaurus.
Howard Hawks' 1964 comedy Man's Favorite Sport? is an intentional homage to Bringing Up Baby, and Hawks only cast Rock Hudson and Paula Prentiss as the leads in the later film after trying unsuccessfully to coax Cary Grant and Katharine Hepburn into reuniting for the project.
The original script had some scenes in the middle of the movie where David and Susan declare their love for each other. These were filmed but not included in the final cut of the film.
The script had an elaborate pie fight but it wasn't filmed.