When Harlan takes Lonnie shooting, he uses a gun that takes 6 rounds. After shooting all six out of one and supposedly shooting four from the other, he offers the gun to Lonnie and asks, "Do you want the last two?" However, five shots from the second gun can clearly be heard before he makes the offer.
During the shooting at night in the hills, Ben had a Fu Man Chu Mustache. He then rides into the daylight into the set for the Western being filmed and Ben is cleanly shaved with no facial hair.
When Harlan and Lonnie are chased away from the campfire, Harlan's mustache is missing in the next scene as they enter the old west town. It is missing from the rest of the film, even though there has been no time for him to shave it off.
Harlan: I've tried living down in the valley again, really tried this time. Walked up and down it looking for one open face, but most people I've meet hardly seem like human beings to me anymore.