Continuity mistake: In the scene where Payne is holding up his fist asking Alex whether he wants him gone or not, his fist changes position. When they do the close-up of Payne, his fist is right by his head. When they show him from the back it is about a foot away from his face. It goes through this 2 or 3 times.
Factual error: During the first few minutes of the film we see Major Payne report into the General. Major Payne then salutes, however, he does not have a cover on his head. As per USMC/Naval Customs and Courtesies, Marines only render the proper greeting of the day when reporting to a superior officer without a cover, they don't salute. (00:03:20)
Other mistake: During the drill performance towards the end, the cadets' rifles bounce around like rubber, but you can hear the sounds of a hand hitting a real weapon from time to time.
Continuity mistake: In the scene when Alex is given his "promotion" and they are standing outside, he tells the Major his first order is to "screw you, sir" and his right sleeve is visibly rolled down while his left sleeve remains rolled up. In the next shot, showing the major, you can see Alex's right arm on the left side of the screen with the sleeve rolled back up.
Revealing mistake: During the first few minutes of the film when Major Payne reports into the general, his belt loop on his Service Alpha uniform is way off regulation. He has the belt loop hugging the belt buckle when it is supposed to be aligned with the end of the blouse pocket. (00:03:20)
Continuity mistake: When Alex is given his promotion you can see that Dotson does not have the rank insignia on his shirt lapel as Payne walks out however in the next scene you can see Dotson exiting with the rank insignia on his shirt lapel in the background when Alex is arguing with Payne.