Executive Meddling: Hitchock and screenwriter John Michael Hayes clashed a lot during production, as Hitchcock wanted the film to go a different way than how Hayes did.
Uncredited Role: Alec Coppel (best-known for co-writing Vertigo) made uncredited contributions to the screenplay.
What Could Have Been: The original script's ending resolves a lot more than the actual film's ending does, including the arrest of the Big Bad (though the scene blatantly hints that he and Danielle have a getaway plan in the works.) But apparently much to the scipt writer's dismay, Hitchcock changed it so that the film ends rather abruptly and with a joke. Hitchcock had wanted to do something similar with Strangers on a Train, end the film at Guy's acquittal, but the studio wouldn't let him.