Revealing mistake: While Bishop and Steve McKenna are practicing with various firearms, a slow-motion shot in the film of Steve shooting a .50 caliber rifle shows that, while the sequence depicts him firing "live" rounds, the extracted shell casing is from a "Blank" cartridge (evidenced by the crimped forward portion of the brass casing).
Visible crew/equipment: In the scene where Bishop gives Steve the first aid kit after Steve's first kill you can see a boom mic in the upper part of the screen.
Factual error: When Bishop and McKenna are discussing how to kill the preacher, Bishop states that epinephrine and adrenalin are a lethal combination; they are actually two different names for the same thing.
Visible crew/equipment: In the scene where Arthur and Steve visit the bar together, a mike is visible as Arthur gets his coat.
Continuity mistake: In the scene where Bishop and Steven are being chased on the skyscraper, after killing Vaughn, Steven encounters a man coming out of a blue door. Steven disarms the man and fires 2 shots into him, yet there are 3 bullet holes in the door behind him.
Factual error: They are supposedly in Chicago when they are fighting on a high rise building. The building is actually the world trade building in New Orleans. Harrah's Casino and palm trees are visible when looking down in one scene.
Factual error: There is a night scene showing aircraft at the airport. Clearly shown are a Continental 747 and DC9. The tail colors are the old Continental "meatball" colors that were put on in 1968 and then changed to a blue & gold beginning in 1991. By the year 2000, Continental was no longer flying any 747's, and this film is set in modern times.
Factual error: In modern automobiles, like the late model BMW Bishop enters with a "slim-Jim" before the final chase, entry without use of the appropriate key or fob will result in the alarm going off and all the car's systems becoming disabled within 30 seconds. A tow to the dealer is then required. If Bishop had appropriate equipment to start the car, he would not need a "slim Jim" in the first place.
Continuity mistake: The pearl handled gun that Harry Mckenna pulls out of the garage has stamped on the right side, Auto-Ordnance Corp, West Marley NY and a serial number of TGM10263. At the end of the movie, when Steve Mckenna dies and the gun is on the ground, it is a different gun. Now on the right side it has stamped, United Stated Property M1911 US Army and a serial number of 949186.
Character mistake: 2 men are watching the cameras with Bishop rolling away from the exploding truck. One man says to watch camera 2, but they are actually showing 1 in the upper left corner.
Continuity mistake: In the end, when Steve McKenna is filling the car with gasoline, after he says it is Arthur's last chance for buying something in the shop, the gas hose is out of the car, and Steve is opening the cap, whilst he already started fuelling the car. Next shot, he takes the hose out, and displaces it.