Illinois Gordon (Chi McBride) gives his cousin Bumpy Johnson (Laurence Fishburne) a Colt Official Police revolver, which he uses throughout the entire movie to take over Harlem. At one point, Bumpy's girlfriend Francine (Vanessa Williams) is forced to shoot assassin Albert Salke (Mike Starr) with the revolver.
M1911A1
Many of the Harlem gangsters in the film use M1911A1s. Whispers (Paul Benjamin) carries two, one on each hip, that he draws several times. Dutch Schultz (Tim Roth) and his bodyguard, Lulu Rosencrantz (Ed O'Ross) both carry 1911s, one of which is eventually used by Lulu to shoot his boss in the Palace Chop House bathroom.
It looks like Schultz's 1911 is a Series 70 1911, which would not have existed back then, so its presence in the movie is an anachronism.
Smith & Wesson Model 10 Snubnose
Illinois Gordon (Chi McBride) carries a nickel Smith & Wesson Model 10 snubnose revolver, which he gives to Bumpy before his death at the hands of Capt. Foley.
Smith & Wesson Model 10
One of Dutch's hitmen uses a Smith & Wesson Model 10 during the attempted murder of the Queen (Cicely Tyson) and Bumpy on their way to the opera.
Suppressed Revolver
Albert Salke (Mike Starr) and Jules Salke (Beau Starr) use a "silenced" revolver to kill the guard at Bumpy's building during their attempted hit, following the classic movie myth of having a suppressor work on a revolver.
Thompson M1928
Dutch's gunmen use Thompson M1928s during their attempted hit on the Queen and Bumpy. After killing one of the hoods, Bumpy picks up the Thompson and fires back at them with it.
Remington 870
Bub Hewlett (Clarence Williams III) carries a sawed-off Remington 870 when Dutch's men raid the apartment at the end. Several other sawed-off 870 shotguns are used, some without their stocks.