Visible crew/equipment: In the shot where Dirty Steve is on his horse, he asks, "Hey Dog, did you see the size of that chicken?", and then he fires his shotgun. You can see someone's hand come up to grab the reigns of the horse. (00:43:25)
Continuity mistake: Near the end when they're entering the Mexican village, Billy's coat disappears as he rides through the gate. (01:17:45)
Continuity mistake: When Tunstall arrives at his place with Billy for the first time, Tunstall is clean shaven. At dinner that same night, he has a mustache.
Continuity mistake: The knife in the post is first pointed up, then pointed down.
Chosen answer: He may have. When Billy started whistling, the bounty hunter's face changes. He continues to speak to Billy in a dismissive tone, but does eventually pull the trigger (although Billy had unloaded the pistol). Hard to believe he would just shoot some mouthy kid in a bar.