Continuity mistake: During the initial standoff between Ben Brigade and Billy John, the natural light varies in the different camera angle - just look at the way the sun shines on Randolph Scott's jacket.
Continuity mistake: When Brigade at the end of the movie tells Boone that he'll be the one to get him, Mrs Lane's hair is on/off her shoulder between shots. (01:10:35)
Continuity mistake: Frank approaches the dead tree, and Brigade tells him "That's close enough." In the background, the henchman with the hat that is most frequently shot on his own, separate from the others, is on the horse completely still. In the close-up, he's having a hard time keeping him quiet. (01:07:05)
Continuity mistake: When the cowboys stop by the dead tree, their positions change at the cut ("And have it over"). (00:52:30)
Continuity mistake: In the first close-up of the big evil that is Billy's brother, Lee Van Cleef's face is lit under a totally different light (when he says "It ain't the money that Brigade wants. Not the money at all"). (00:50:05)
Continuity mistake: Whit and Boone are watching the freshly widowed Mrs. Lane and entertain some fine vintage sexist talk about her need for a new man. At the end of it, Boone slaps his buddy with a wet hankie on the cheek and it limps on the shoulder. James Coburn laughs and squeezes his buddy's gift tight in hand, but in the next shot it is back on his shoulder. (00:41:35)
Continuity mistake: When Whit helps Boone to shave, he holds the mirror by the left or right corner depending on the camera angle. (00:40:00)
Continuity mistake: The numbers of the Mescalero raiders that attack the party change repeatedly throughout the scene. There are 10, Ben shoots one down, there are still 10 when he drops another one, he kills a third, still 10 attack, and so on. (00:28:30)
Factual error: When Mrs. Lane screams at the sight of the horse, on the back of Karen Steele you can see the outline of a modern bra under the shirt. (00:23:30)
Continuity mistake: The party decided to leave the station. Brigade sets the horses free. Mrs. Lane has something to say about it; as she calls Brigade by name, Boone in the background turns around between shots. (00:20:15)
Continuity mistake: At night, Boone tells Ben the reason of his presence in that part of the country. As he is about to leave and Ben calls him by name, he is holding the ladle in opposite directions between shots. (00:19:35)
Continuity mistake: Once the coach crashed into the fence, the right arm of the dead driver changes position between shots. (00:12:30)
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: Sam Boone walks Ben Brigade to the horses holding his rifle, and they have a bit of a chat by and about the captive Billy. During this scene, the handkerchief at Randolph Scott's neck waves like mad in the wind over his shoulder under one camera angle, and it is still and in front of the chest in the other. (00:09:30)
Continuity mistake: The last night before the supposed arrival to Santa Cruz, Boone approaches Mrs. Lane. The moonlight (actually a rather obvious day-by-night) shines on her fully, but as the camera switches to a close-up, suddenly there are all sorts of shadows of foliage over her blouse. (00:57:20)
Continuity mistake: When Ben reiterates "We're going to Dry Fork", Randolph Scott's hands are joined on the reins. Shot from behind, you can see by the arm position that they are apart. (00:20:45)