Factual error: Warren Beatty refers to the "Hoover Dam" being able to generate the power needed for Las Vegas and his Flamingo casino. The problem is that he supposedly made the comment in 1937. At that time, the "Hoover Dam" was still called "Boulder Dam." It wasn't renamed to honour President Herbert Hoover until about ten years later.
Factual error: Bugsy was not watching a film when he killed just reading a news paper. He was not alone in the house - Hill's brother and a close friend of Bugsy were upstairs asleep, heard the shooting and called the police.
Factual error: At the end of the movie Virginia Hill is told of Bugsy's death at the hotel in Las Veges In truth she was in Europe after she was "told" to get out of America. She did not return for four years.
Factual error: The Lincoln Continental shown in the beginning of the movie is a post war model as evidenced by the grill. This scene is during WW II so it should have been the prewar model. It is very close in appearance to the 1942 model but it is not one.