Anachronisms: In Virginia's "fear of flying" scene at the airport, there is an airplane hangar with a sign for "Mobil" attached to it. The "Mobil" design seen was not introduced until the late 1950s. The movie is set in the mid-1940s, and the design that would have been used at that time was Mobil's logo of a white shield with large red Pegasus (flying horse) trademark and the name "Mobilgas" in black.
Continuity: The smoke coming from the candles on the birthday cake disappears and reappears between shots.
Crew or equipment visible: After Siegel (allegedly) murders Greenburg, and as the car containing him and Virginia Hill begins to pull away, you can see in the right rear fender the reflections of two people. One is easy to identify as a human figure, the other looks like someone is possibly hunched over.
Anachronisms: The cars in this film were very authentic except for the 1948 black Lincoln continental in 1944
Anachronisms: During the shrimp dinner at which Virginia throws the ashtray at him, Bugsy is reading a newspaper with a headline about Allied troops crossing the Rhine. Rhine was crossed in 1945, long after Mussolini was already deposed (July 1943), yet Bugsy continues to advance his plot to assassinate Mussolini.
Continuity: After Bugsy's house has been sold to finance the Flamingo Club, he takes another look at his "screen test". He's at Virginia Hill's mansion, but he looks at the film in the projection room of his old house.
Revealing mistakes: In the scene where Virginia is shooting all the ammo in Bugsy's .45 pistol, when the last round is fired the slide should stay in the "open" position rather then the "closed" position which it stays in.
Factual errors: The film takes several key historical liberties, especially with the Flamingo and Bugsy's dealings with his fellow mobsters.
Factual errors: Harry Greenberg was in fact murdered in November 1939, not in 1945 as depicted in this film.
Factual errors: In the scene where Bugsy is viewing an outdoor patriotic rally through a basement window, all the American flags are hanging incorrectly. They are displayed with the blue fields in their upper right corners, when in fact the fields should be in the upper left corners.