Factual error: In the scene where there is a train passing, the cars are marked "Burlington Northern." There was NO Burlington Northern until 1970, 7 years AFTER the shooting.
Factual error: Morrison did finish film school in real life. He did not drop out as depicted in the film.
Factual error: Pierrepoint is depicted as having a London accent. In real life, however, he was from the north of England, and had a Yorkshire accent, which sounds completely different. This is proved in a BBC interview with him, dating from the 1970s.