Other mistake: At the beginning of the episode, Lucas and Mark are riding their horses and discover a large footprint of a cougar. Near the end of the episode, Lucas is riding in a different area and sees another cougar footprint. The close-up of the footprint is the same one that was shown earlier. (00:01:00 - 00:21:00)
Requiem at Mission Springs - S5-E22
Other mistake: After Mark falls from a horse and is paralyzed, Doc Burrage recommends that Mark soak his legs in the Mission Springs mineral spring. Lucas, Mark and Lou drive a wagon to the site. At night they all complain about how cold it is and there is a steady sound of wind blowing but all the trees and bushes are motionless.