Character mistake: Reward poster on the pillar for Matt says "Matt Dillion", not Dillon.
Character mistake: When Festus is arresting his cousin portrayed by Shug Wooley, as he helps him up off the floor, he distinctly calls him Henry when that cousin's name is Emory.
Suggested correction: He calls him "Emery." He even says his name earlier in the scene shortly after he walks in and he pronounces it the same way. There wasn't even a character or actor in the episode named Henry, so it's not as if he mixed up the name.