When Pitchfork Napier is taunting Billy Ray in the desert, the inkwell is full/empty between shots when Billy Ray passes out after watching Dancing Bear scalp Napier.
After Billy Ray shoots his second horse, as he walks away from the body, the horse can be briefly seen getting back up on the right side of the screen.
During the panorama of the desert mountain range, film crew's cars can be seen parked in single file on the road.
When the heroes trick the guards of El Diablo's hideout into taking a group picture, the last guard that dies is shot with two arrows, and the second arrow has a guiding wire that is clearly visible.