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.
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Continuity mistake: When Noodles is raping Roberta in the car, her socks are pale brown-grey, then camera angle changes, and they are black, and then they are grey-brown again.
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Factual error: Noodles visits the mausoleum containing the caskets of his friends who were killed in 1933. He finds a key hanging on the wall from a plaque that says Noodles built it in 1967. Earlier, he tells Fat Moe he had not been in town for 35 years, since 1933, so the action was taking place in 1968. The key is to a locker at a bus terminal. Inside the locker is a suitcase full of money, stacks of twenties. The bills have the signature of Secretary of the Treasury William Blumenthal, but he was appointed by President Carter in 1977.
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More mistakes in Once Upon a Time in America
Question: why, being there so many sequences of nudity in the film, the woman in the funeral car Max brings for Noodles after he is released from jail has her breasts blurred?, why would this scene be conceived like that?.
Chosen answer: You have a censored version. The American R1 version has no such censoring.