Continuity mistake: When Buster is shot, his hat with the hole in it disappears.
Audio problem: When the band is marching with the Massingale rally one can hear flutes and many band instruments, but the band consists of only a few brass instruments.
Factual error: Steve Judd makes a ten cent bet with Gil Westrum and plops down his dime. When we see the dime we see the worn reverse of a Mercury Dime. Mercury Dimes were not released until October 1916. This movie is set in the early years of the 20th Century, many years before Mercury Dimes were placed in circulation. (00:06:55)
Continuity mistake: After Isaiah kills a bear, Otter Bob holds out a bottle of liquor at him. In the close-up, Bob is holding the bottle by the neck. In the wide shot, he's holding it by the body.
Plot hole: The women leave the bordello and cross a waterless, hot mineral desert to reach Jericho. Meanwhile the posse that arrives at the bordello behind them takes a different route and catches up with them near the mine. Why didn't the women go that way?
Continuity mistake: Baxter and Beecher are riding in a horse-drawn wagon. As they go across a bridge, the train carrying the Marx Brothers approaches. Baxter and Beecher leap off the bridge, one jumping to the right and one jumping to the left, but they are side by side when they land in the river below.
Continuity mistake: In a saloon, Moe and Curly are playing poker with Longhorn Pete, the proprietor. Among Curly's five cards are an ace of hearts and an ace of diamonds. Moe's cards include an ace of spades and an ace of clubs. They pass some of the cards to each other under the table in the hope that one of them will wind up with all four aces. When their cards are shown again, Curly and Moe each have an ace of spades and ace of clubs. The ace of hearts and ace of diamonds have disappeared.
Continuity mistake: The sheriff wears his badge over his left side, which is traditional. As he is approaching on horse in the final scene of the movie it is still on his left side. Then for a few seconds in one shot his badge is on the right. (01:23:10)
Factual error: In two, maybe three scenes, there are ring-necked pheasants. One is early in the movie as the Jameses ride past a butcher shop where ducks and pheasants are hanging up for sale. One is mid-way in the movie in the scene of the house- or barn-raising and big picnic. The movie supposedly took place in the mid-1870s. Pheasants were not imported to America from China until 1881.
Factual error: Two grave markers at the end, approximately one hour and 27 minutes into the film, have the date of November 7, 1889, on them. The script made it clear that the climactic gunfight between Glenn Ford and Broderick Crawford came on a Sunday. Ford was called out of church services, for example. According to The World Almanac and Book of Facts, November 7, 1889, was a Thursday, not a Sunday.
Revealing mistake: Why does the railroad station look so old? It should be almost new at the time of the film.
Factual error: This Warner film concerns a pair of post-Mexican War, new-style percussion revolvers stolen from a travelling arms dealer and used in a crime spree. The criminal was unbeatable because of the overwhelming firepower of the guns compared to the single-shot handguns used by everyone else in the film. The title guns used throughout the film were a pair of Colt Dragoon revolvers, in caliber .44. Colt didn't manufacture a .45 revolver until the metallic cartridge era, in 1873.