Other mistake: Early in the movie when Shale is screening the commercial for his "services," the rolling text describing his abilities lists "Helicopter Repelling" instead of "Helicopter Rapelling".
Continuity mistake: When Shale gets in the fight in the library, he takes a round to the upper left chest. When he takes the shirt off to reveal the vest there's no bullet and no damage to the vest.
Continuity mistake: When Shale goes to interrogate the guy at the Jai Alai court the guy tries to hit him with the balls. He puts one in his cesta (the scoop on his hand) and it falls out as he tries to launch it but a ball still launches at Shale.
Continuity mistake: Rollie breaks the paddle behind his desk, but later on in the movie you can see it behind him and it's unbroken.
Visible crew/equipment: At the shooting range you can see a reflection of the filming camera in the mirrors as it moves in front of the building.
Continuity mistake: At the end of the fight on the beach, the Seminole is too far away to have hit Shale.
Revealing mistake: Look at the gun fired behind Shale at the firing range. The person doesn't pull the trigger, there is no flash, the slide doesn't move, there is no smoke. But the gun still kicks.
Plot hole: When Tom Berenger is talking about Vietnam, the school bell rings and everyone leaves class. After everyone leaves, Tom Berenger puts the ice pick in his overcoat and quickly picks up his briefcase and opens it. Around 10 to 20 seconds after the bell rang, he looks at the portable surveillance in the briefcase. He flips through all the cameras. How did the entire school clear out with no one in site from the time the bell rang? Are there not usually some people around in the hallways after school?
Continuity mistake: While Shale is hitting the Wolfson in the Jai Alai facility with the helmet, there is some blood around his head but in the next shot there is blood around the mouth too.
Continuity mistake: The day after Shale's SUV crashes into the house trailer, he is shown driving it to school without a scratch on it.
