When Jace decides to "scare" Lane, he fires 12 shots at him--far beyond the capacity of his rifle.
The sousaphone shown when Will Lane interviews Sister Sue was not invented until 1893 and this movie takes place in 1890.
Boom mic shadow visible on Jace's hat when he and his gang ride up to Will Lane and Lee Carey at Carey's place the morning after the fight in the saloon.