Continuity mistake: When Colonel Marlowe blows the bridge near the end of the film, a pair of spectacular explosions ensue, tossing planks and beams into the air. However, as Hannah Hunter gazes at his retreating form, the bridge is still intact.
Continuity mistake: When Rick Nelson tells Angie Dickinson to throw the plant pot through the window to distract the gunmen who threaten John Wayne he seems to have had a hair cut between scenes as his sideburns are halved by the time he reaches the street and grow again later.
Continuity mistake: Mrs. Carrie Lane puts some respect in the rough cowboys with her rifle. As Boone moves towards her and asks for Ben Brigade for some moral support, the horse Billy John is on moves away from the other horse quite a bit. The horse is back in line at the cut. The natural light also changed. (00:11:05)
Continuity mistake: When Bugs is performing his shooting stunt in the saloon, you can see the entrance behind Sam has nothing between it. When Sam tells Bugs he's missed, we cut to Bugs who says "Wait!" and then return to Sam, and this time there are doors between the entrance.