After Franco is hit with his own dart, Will and Casey switch positions between shots.
At numerous points during the fight between Franco's men and John, the actor playing John is clearly being doubled by several stunt men, one with a bad wig and one with dark hair.
When Casey is checking Franco's files in the CIA archives he is faking to communicate to the servers, but in fact he is just typing into a Commodore Amiga Notepad, which is just a simple word processor (using a file called "Top Secret.doc").
Obvious Asian stunt doubles for a few of the characters, including Franco's stunt double with the misshaped white wig.
The phrases "ACCESS DENIED" and "ACCESS PERMITTED" are very obviously typed in a word processor; the speed at which the characters appear and the presence of a vertical cursor bar are obvious clues.
A safety floor mat is visible when the bad CIA guy is shot and falls down in the airplane hanger.
When Will drives up to Casey's house, he stops directly in front of the crew who are then reflected in the car door.
At the very start of the film, when all the police cars are lined up outside the bank, the camera car is reflected in the fenders of the police vehicles as it drives slowly past.
At the start of the movie when Will and Casey's dad is cutting the cake, the boom mic is visible above them.
At the end of the bar fight as Angel walks over to Casey the boom mic is visible in the large mirror over the bar behind them.
Near the end when Franco reveals he has captured Maria a long black boom mic drops into view above their heads for several seconds.