Uncle Willie carries the bag of gold in his right hand to give to the head of the bandits, Jack Lester; when the bandits initially confront him he is still holding the bag of gold in his right hand. Suddenly, Uncle Willie is hiding the gold under his left arm beneath his jacket, the same place he had put it back in the bank when it was handed to him.
When Uncle Willie goes to the bank to confront Clanton and Lester, his hat is back to front in close up, but switches back the right way in long shots.
Song played during dance was "Red River Valley". This movie takes place in 1863, but this song was written in 1879.
During the final shootout scene a barrel is thrown through a window of the saloon. The internal scene is obviously painted on a sheet, which moves when the barrel hits it, also revealing creases.
When the new safe for the bank arrives Uncle Willie McLeod says it's "built like a battleship." The story takes place in 1863. The term "battleship" did not come into wide use until the late 1880s.
In the opening of the film they show a train with Utah Southern Railroad on the tender. The story takes place in 1863 and the USR did not operate until 1871.
The story takes place in 1863, during The Civil War. Just before the horse stampede through town a character says, "...they'll think they're riding into Custer's Last Stand." Custer's Last Stand happened in 1876.
The song, "Little Brown Jug", (heard at the dance), was written in 1869 while the 'book' at the start of the film indicates that the film is set in 1863.
The Hank character compares the coming shootout with the outlaws with Custer's Last Stand. The story takes place in 1863. The Little Big Horn would not occur until 1876.