When Tommy enters Reggio's mansion, he clearly gets shot in the right shoulder/arm. His arm just hangs at his side and subsequently he carries his gun in his left hand. When he reaches the basement and finds his brother Vincent, he is shown carrying the gun with his right hand with his left arm being limp. In the same scene, he finishes clearing the room and has mobility in his left arm again to grab Vincent. Then when he gets shot in the back, he is back to having a limp left arm and shoots the bodyguard with his right hand.
When James Marsden's character is dropped off at the diner after his first night at the bar, his hair is considerably longer than the buzz cut he has during the entire film.
Joey fires the remainder of his shots in the bedroom at Reggio's wife, the slide retracts on the gun which is an indication that the gun is empty, the gun falls to the ground but moments later Joey retrieves the gun and the slide is now released.
When Tommy and Brandy kiss, the position of their heads change depending on the camera angle.
In the beginning when Tommy is shot and the car is driving away, a Pontiac Vibe can be seen in the background. These cars did not exist in the early 1990s.
Throughout the movie, the characters are always using their flip cell phones which were not around in 1991.
Set in 1991, closeup shots of drug money/bribes show US currency with the large portrait anti-counterfeiting design that wasn't introduced until 1996 and after.
In the scene where Tommy gets Brandy's son his medicine, the Pepsi fridge in the background has a blue Pepsi bottle on it. The label was changed late 90's. In 1991, when the movie is set, it should be the more classic white can.
Location errors abound as the story is based in Philadelphia. Most telling are: a Steelers logo on a beer billboard in one scene (would be an Eagles logo if in Philly); the Allegheny County '412' area code on a sign on a building for lease, late in the film; The PPG famous spiked tower in the background; famous Pittsburgh yellow bridges throughout; and key scenes at 'Wholey's' which is a real meat and fish landmark store in Pittsburgh's Strip District.
Near the end of the movie, Tommy sits on a bench and waves a
red and white PA Transit bus by, this bus is for the Port Authority Transit of Allegheny County, the bus system in Pittsburgh; in Philly the bus would have been a SEPTA bus (South Eastern Pennsylvania Transit Authority).