Character mistake: During the trial, Danny says Lt. Col. Markinson shot himself in the mouth with a .45, but in the suicide scene, Markinson's gun is a Beretta 9mm, the standard-issue U.S. Military sidearm.
Character mistake: Some of Colonel Jessup's ribbons are in the wrong order, and his Combat Action Ribbon is backwards.
Character mistake: When LTJG Kaffee says "whatever happened to saluting an officer when he leaves the room?" It's well known that Kaffee doesn't know much about military protocols, but Marines and Sailors do not salute while uncovered, especially indoors. Army/Air Force maybe, but not the Navy or Marine Corps.