Character mistake: When Rosie sticks her revolver in Bond's room and Bond flips her onto the bed, Bond incorrectly identifies the gun as a Smith and Wesson .38 which would make it a model 10 or 15. It was actually a Model 19 .357 Magnum.
Character mistake: At Duke Boudreau's bar, the potential recruits for the sting are told, "Gondorff is setting up a con on the North side". Later in the film, Agent Polk tells Lt. Snyder, "Gondorff is running a con on the South side". The actual address for the betting hall is not given, but it is just down the alley from Klein's, which does have a South side address.
Suggested correction: It's possible recruits were given the wrong information on purpose until they'd been cleared for participation. Misinformation is a good way to confuse and delay any unwanted attention.
This does not correct the posting. "Polk" tells Snyder that Gondorff is running a con on the NORTH side, which is incorrect. He has absolutely no reason to try to mislead Snyder.
Character mistake: When Frank Serpico is recording his phone call regarding being transferred, the guy, who says the precinct is clean as a houndstooth, calls him Mike.
Character mistake: On finding Harman's dead body in their caravan, Charley says 'You called it, kid'. Great line, but Harman didn't call it. Charley, in fact, called it by giving his address to Jewell., who passes it on to Molly, who then goes to kill both Harman and Charley if he can.
Character mistake: When Harry walks up to look in the car which Ricca and his men were shot in, he places his hands on the driver's side and back seat passenger's side window sill, while the crime scene is being investigated. No senior Inspector like Harry would do this. (00:09:40)
Character mistake: After Clinton's phone call, Christine talks with her assistant and making fun of the "mourning", she says "We went directly to Streisand's opening at the Sands right from the cemetery." However, in Vegas Barbra Streisand never performed at the Sands; she did the International (then Hilton) and the Riviera. (00:05:15)