When Kelly drops the rope down to save her dad, it is clearly long enough. Then it's too short, then in the next shot the rope is long again.
When cadets Kelly and Carla walk to Kelly's house to pick out dresses for the dance, they are wearing bags across their shoulders. As they enter the house, the bags are gone.
In the beginning of the film the cadets wear the JROTC patch on their shoulder; this patch is designated for cadets in high school. During the obstacle course scene it changes to the ROTC patch which is designated for college students.
When Major Rigby picks up Kelly's dropped rifle, it is pointing in a different direction than when she dropped it a second before.
When Kelly does her impromptu routine with Jennifer on the field, her rifle disappears.
In a scene when Kelly is going through the obstacle course, one of the course instructors wears the 1st Cavalry Division patch on his uniform. The movie takes place in upstate New York, and an officer from the 1st Cavalry Division wouldn't likely be that far north as the division is headquartered and located at Fort Hood, Texas.
At the beginning of the drill competition at the end of the movie the Marine drill instructor that asks a Navy cadet what the 13 strips on the flag represents, is actually out of uniform. Per regulation only mustaches are allowed, so him having a goatee is out of regulation.
When Cadet Captain Stone approaching her platoon at the beginning of the movie she has her hands in her pocket, it is against regulation to have hands in your pockets.
A sign in the background reads, "You always miss 100% of the shots you don't take." The word "always" is redundant. It also does not appear in Gretzky's original quote.
At Kelly's trial, Carla says "It's just paint", but her mouth says something else.
Sir calls Brad "Cadet Captain Rigby", instead of Cadet Major Rigby when telling Kelly she made the drill team.