Continuity mistake: Late in the movie, Billy is captured and jailed in an upstairs room with Bell to guard him. A knock sounds at the door and Bill raises his rifle (cocked) and points it at the door. The door is opened revealing a lady. Bell, still aiming the rifle (now suddenly uncocked), quickly lowers it.
Continuity mistake: In the first part of the movie there is a scene where Billy rides into Old Fort Sumner with the gang. He then goes into a building and meets a guy named Beaver. When Beaver is first talking to Billy he is wearing an eye patch over his left eye. A minute later he is seen talking to Billy (about the soldiers coming and harassing him) and the eye patch has mysteriously disappeared.
Continuity mistake: During the scene at White Oaks, it is a different door when they are inside the house compared to the door when they are outside. One side has the glass at the door knob, the other side it's 3/4 the way down the door.