When the rifleman is preparing to ambush Jack Cole and he looks through his telescope, it is obvious that the horse Jack is riding changes from the striking white-faced one to a plain brown.
The same blaze faced horse shows up later being ridden by one of the Moat family.
When Lucas Moat dies, his position changes between shots.
When Lucas Moat dies, his son's hands change position between shots, when they are holding him.