Character mistake: When Tracy is about to announce that the wedding is off, she turns to Dexter for help, and he says "Two years ago..." Tracy starts the announcement "Three years ago..."
The Philadelphia Story (1940)
1 character mistake
Directed by: George Cukor
Starring: James Stewart, Cary Grant, Katharine Hepburn, Ruth Hussey
Revealing mistake: In the scene where Cary Grant punches Jimmy Stewart: Jimmy starts falling back (and you hear the sound effect of the punch) when Cary's fist is a good 1-2 feet from Jimmy's face.
Elizabeth Imbrie: What's this room? I've forgotten my compass.
Macaulay Connor: I'd say, south-by-southwest parlor-by-living-room.
Trivia: All of the scenes in this movie were shot in only one take and in one scene the technique really shows. When Jimmy Stewart is drunk, he ad-libbed hiccuping while he was talking. Cary Grant, not expecting the comic relief, had to look down at the floor to keep from laughing (you can see him grinning and collecting himself).