Continuity mistake: When Jesse and Frank are telling the doctor that his son was killed (right in the beginning of the movie) Jesse gained a lot of beard growth in five minutes. When they are outside talking to Zee, he has just a light beard, and then when they go inside he has a heavier one.
Factual error: During the final shoot-out, when Raf shot the man on the roof as he enters town, the wrong flag is displayed - a 48 star flag, but the time setting is the 1880's, when there were fewer states.