Factual error: Kuklinski is looking at a newspaper which is dated January 3rd 1983, and the text reads that Roy DeMeo was found dead the previous day. In actuality, Roy DeMeo died on January 10th 1983. (01:22:55)
Revealing mistake: When Ray reminisces about having fought the Germans in WW2, a flashback is shown with him fighting in a bunker. He is carrying a No.4 Lee-Enfield rifle which requires the bolt to be worked after every shot to reload. However, he is shown firing two shots in rapid succession without moving his hands at all, revealing the shots to just be flashes added after filming.
Continuity mistake: While he is copulating with Laurence, François Monge receives a phone call from his boss about the murder case in Bobigny. To shush his vocal partner, he gives her a slap on the shoulder, but he does it with the right hand in the view from behind, and the left hand in the full frontal. (00:08:55)
Continuity mistake: In the car after Martin tells Hans about the throat slitting story, Billy and him get into an argument about the violence of the story. Billy says "It's going to be violent, it's about seven fucking psychopaths!" Martin then says "Hey!" But you can see in the back seat his mouth doesn't move for that. Then it cuts to a close up of Martin and his head is in a different position, facing Billy where he was looking out the window a moment before. (00:58:05)
Continuity mistake: Sheila is clutching the phone to her chest with both hands, since Melinda is reaching for it to delete the butt-flexing video. The door chimes and the bearded man enters the store; in the foreground Sheila is in a different position with her arms crossed, and in a third one with her arms down at the next cut. And even more noticeable, a 4th different one as she walks away, holding the phone across the chest to the opposite side of her body all of a sudden. (00:07:50)
Continuity mistake: After Mike has set the tent up they go for a ride on their snowmobile to check the scenery out. They come uphill parking the snowmobile facing upwards. They get up looking at the scenery, and a few shots later the snowmobile has suddenly turned 180 degrees facing downhill. (00:13:40)
Factual error: The movie changes between a basketball season and a playoff basketball game then to a baseball game being played in what looks like early summer...back to a team getting ready for the basketball playoffs. The two seasons don't overlap.