In Luciano's close ups, his right eye is not open as much as the left. On many historical pictures of the real Lucky Luciano his right eye is partially closed as well. This was due to a knife injury during a 1929 abduction by unknown assailants that damaged muscles in his right cheek that prevented his eye from working properly.
Although Ellsworth "Bumpy" Johnson, Dutch Schultz, Lucky Luciano, and Stephanie St. Clair existed in real life, the movie is fictional and only loosely based on incidents in their lives during this time period. Many other characters, including Francine Hughes, Captain Foley, and Calvin, are wholly fictional.
An old friend of the real Lucky Luciano allowed Andy Garcia to wear Lucky's pinkie ring for one scene. You can see it when Lucky gives Thomas Dewey the bribe money at the whorehouse, when the prostitute takes the cigar out of Lucky's hand.
Actor Clarence Williams III who plays the character Bub Hewlett, a rival of Ellsworth "Bumpy" Johnson's, would go on to portray Johnson in the first few scenes of American Gangster (2007) 10 years later.
Dutch says to Lucky: "I'm going to the library. I'm going to take out that book "How to #*%& friends and irritate people." Here he is parodying the popular self-help book by Dale Carnegie, "How to Win Friends and Influence People." Published in 1936 and an instant best-seller, the book would have been discussed widely in social circles during the time of the film.