Strangers on a Train (1951)

Factual error: When Bruno is on his way to Union Station, he's heading on a bridge away from the Lincoln Memorial, which means he's leaving Washington D.C. for Arlington, Virginia, or in other words, he's going the wrong way.

Plot hole: Farley Granger meets a math professor on a train bound from New York to Washington, and is able to prove as much to the police. The professor got on in New York and got off in Wilmington, DE, while Granger boarded the train in the fictitious town of Metcalf, NJ, and rode on to Washington. Thus, they met between Metcalf and Wilmington. But the police say Granger could have boarded the train in Baltimore, by which time the professor would have gotten off and they never would have met.

Other mistake: When Farley Granger sneaks out of his flat to go to Robert Walker's house, there is an EXIT sign over the door. Maybe in a theater or cinema, but in a private apartment?

Trivia: When mom exposes her pretty scary painting to Bruno it very much resembles the key scene in the film "The Picture of Dorian Gray" from 1945.

S.Holmes

Trivia: Early in the movie, Alfred Hitchcock is boarding a train with a double bass as Farley Grainger gets off at his home town.

Bruno Anthony: I have a theory that you should do everything before you die.

Senator Morton: I'll have him called up immediately.
Barbara Morton: Obstructing the wheels of justice, Daddy?

Barbara Morton: Oh, Daddy doesn't mind a little scandal. He's a senator.