Factual error: In the hangar scene when Castor and Archer point their guns at each other, if Castor's gun was really empty the slide would be locked back.
Continuity mistake: After the second speedboat explodes, when Sean (as Castor Troy) pulls the speargun trigger, Castor (as Sean Archer) grabs the spear shaft before it can unload. As he grips the gun, the problem is that in some shots the slings are still loaded, but in other shots they are not. (02:09:00)
Continuity mistake: After being told that Pollux was released from prison, Sean Archer (as Castor Troy) shouts that he's Sean Archer, then grabs hold of the bars above him, with three bars between his hands. Next shot, as the guard's foot is on his hand, there are only two bars between his hands before he lets go. (00:58:50)
Revealing mistake: In the speedboat crash where the film is slowed down, there is a medium shot of Troy and Archer flying through the air. It is very obvious that neither are the true actors.
Continuity mistake: During the speedboat chase, when Castor Troy (as Sean Archer) shoots up the white speedboat that Sean (as Castor Troy) drives, there are numerous bullet holes on its starboard side. Four shots later, when he hits the box on the rear seat, those bullet holes on the starboard side are gone. (02:04:15)
Revealing mistake: In the scene when Castor Troy kills Agent Winters the sky is blue. There is only one cloud just above the fuselage. This cloud doesn't move, at least not that fast as it should as the jet is near take-off speed. The aircraft stands still when the actress falls out of the jet. In the ensuing shot, when the dummy falls out, the sky is overcast and the aircraft moving again.
Continuity mistake: Eve and Troy visit Mikey's grave. When they first go out to the car, it's cloudy and raining, but they get to the cemetery and the sun is out and everything is completely dry.
Continuity mistake: After the jet crashes into the hangar, Sean Archer runs up the back end of a police cruiser, whose three blue flashing lights are completely shattered. In the next shot facing him, when he reaches the car's roof, two of the blue lights have repaired themselves. (00:13:45)
Revealing mistake: When Castor is pushed into the blowing heat from the plane engine by Sean and is thrown back, the man that lands against the grill is so obviously the stunt double; he has a different hair cut than Castor and really doesn't look anything like him.