Continuity mistake: The whole time sequence in the last part of the movie is messed up. After trying to nab the bad guys at the hotel, Tom Selleck goes home and puts his son to bed, then is called back in to work, and then the rest of the film is supposed to be the same evening, but it was already late night.
Continuity mistake: In the first 1968 section, where Noodles rents a car and drives back to his old neighbourhood, watch the background of the wide shot as he is stopping the car. In the close-up that follows when Noodles gets out, two girls have appeared, hanging around a doorway, who were not to be seen the moment before.
Continuity mistake: At the beginning of the film, when Johnny is first climbing the stairway to his apartment, he climbs a flight, then there is a dissolve to imply that it's a very long stairway, and he's shown climbing another flight. You can see the ground floor only one flight below after the dissolve.
Factual error: The scene during Lonette Mckee's rendition of Ill Wind, where coins are poured onto a glass table, appear to be from a later time period. (01:16:00)