During the chase out of Indian county, the white shawl around Charming Jones' shoulders and arms disappears and reappears between shots.
Two different trains were used, creating at least two continuity errors: Charming gets on one train but departs another. Later, the train Jack watches heading for the crossing with the glue is not the same one that almost runs over him.
The tenders of the trains are loaded with wood, but the black smoke they produce indicate that they are really oil-fired.
When Whiskey approaches Cactus Jack in the jail, (@15:50) the bars on the window move.
When Cactus Jack is in the prison cell, and his horse, Whiskey, is outside the window, the window grille noticeably flexes when the horse's head touches it, indicating it is made of wood, but painted to look like iron.
When Cactus Jack is leaning over the cliff to watch Charming bathe, a pole can be seen holding him up as the small tree he is holding onto breaks away. (only visible in open matte TV showings).
Horse stands available when Nervous Elk yells "charge" and all the horses race from out of the stands (only visible in open matte TV showings).
When Cactus Jack is glued to the train track and subsequently stuck to the front of the locomotive, a crossbar for him to hold onto has been mounted on the front of the smoke box that was not there before.
A zipper can be seen in the back of Charming's blue-and-white dress.
Loads of trampolines visible in every shot when Cactus Jack is bouncing around in the last scene of the movie whilst celebrating (only visible in open matte TV showings).
In one scene where Cactus Jack is trying to get on his horse you can easily see a man moving a trampoline under the horse's belly for him to stand on (only visible in open matte TV showings).