While watching Friday the 13th Part III, Dwayne tells his father there is 45 minutes left in the movie. However, the scene they are watching is the final scene in the film.
When Nick and Chet are being chased in the Datsun, Nick shifts gears, indicating he is driving a manual transmission car. However, after he shifts and is performing his 180-stunt, a close-up shot shows his feet and there is no clutch. In a manual transmission car, the pedals are close together, and the brake pedal is smaller due to the clutch next to it.
When Nick and Chet are robbing the bank the vault is opened without anyone opening it.
When he gets in the car the driver starts a clock for 30 minutes (the pizza is cooked). The 30 minutes should start when the order is placed otherwise the driver could just lie about the time.
When Chet is painting the gun, smudges on the car door can be seen. In the shots where the car is stopped, the smudges are gone, also the painted paper is turned. Later in the end of the movie when the van drives next to them, the paint smudges are also not on the door.
The bank guard's gun could not have fired as depicted. A blow to the hammer of a modern double action revolver (like the one carried by the guard) cannot cause a discharge because the hammer block safety remains automatically engaged until the trigger is pulled.
When talking about Kate's promotion, Nick says, "We don't even have a Radisson here." There is in fact a Radisson Hotel in Grand Rapids, Michigan.
In the shot after the Datsun gets flipped by the police car, there are clearly no cops in the car.
When Nick takes the bomb vest off, his T-shirt is soaked in sweat, but not a minute later when they are driving away, his red shirt is dry.
Even though the bank security guard carries a revolver, he is seen wearing a vertical magazine pouch.
Travis says that Kate knocked over his soda and delayed him turning her over to Nick. However, in Michigan the vernacular is to call a soda a "pop."
During the pool cleaning scene, Dwayne is holding the pool skimmer which has some leaves still stuck to it. When the shot changes, the leaf debris is gone.
1:00:01 - 1:00:09 Dwayne SE P990i's numeric keypad is open when he is talking and next scene it is closed.
During the pen gun scene, while Chango (Michael Pena) has The Major (Fred Ward) at gunpoint, as the camera alternates between frontal and rear shots of Chango you can see his trigger finger switches between being on the trigger when seen from behind but outside the trigger guard and resting along the frame when seen from the front.