Continuity mistake: Seymour watches in horror as the wino is run over by the train. In the long shots, Seymour's hands are waving up and down at his sides. In closer shots, however, he's holding his hands up to his face and screaming.
Continuity mistake: Frank walks into Det. Fink's office. He sits down and lights up a cigarette as they are talking about the missing railroad detective. The cigarette is hanging out of his mouth until a cut to a closeup, and now there is no cigarette. When it switches back to a wide shot, the cigarette is back in his mouth.