Character mistake: When Ellerby tells Sullivan "Some people don't trust a guy with an immaculate record. I do. I have an immaculate record." Really? An immaculate record even after you punch they guy's lights out for not installing the cameras right? He's a captain, had a long career, if he punches a guy for that, certainly he's had other complaints before too.
Character mistake: During the funeral at the end before the 21 gun salute, the NCOIC called for "half left face", that would cause everyone to get shot in the face.