Factual error: John Blair rides for the pony express, which operated until October, 1861. However, all of the handguns in the movie are cartridge Colts, which did not come into existence until 1871.
Factual error: The movie "Santa Fe Trail" (1940) starring Errol Flynn, Ronald Reagan and Raymond Massey, is the story of John Brown's raid on Harper's Ferry in 1859. The president is shown to be Abraham Lincoln, who wasn't inaugurated until February of 1861.
Other mistake: The objective of the band is a cache of gold hidden some years ago in the firebox of a wrecked locomotive in the wilds of Northern Mexico. When they finally dig the firebox door out and open it, the strongbox is sitting inside a completely clean firebox, with nary a cinder, ash, or chunk of burned wood in sight. If the loco and cars had been abandoned after the derailment, there would still have been residue in the firebox.
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.
Continuity mistake: When Buster is shot, his hat with the hole in it disappears.
Continuity mistake: At the very end of the show when Marshall Cass Silver gets in the carriage with Sally, Sally enters first, sitting on the left and him on the right. When the next shot shows them riding off together in the carriage, they have switched sides.
Revealing mistake: On the way to the border, after Gabrielle has died, when the camera pans it on her face, you can see her eyelids shift and blink.
Revealing mistake: While Billy and Eli are on the river, with Eli in the front and Billy in the background, pay attention to Eli's paddle. When it passes in front of Billy, you can see right through it to see Billy through the paddle. (00:56:25)
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.
Continuity mistake: Otter Bob holds out a bottle of liquor at Isaiah after he kills a bear. In the close-up, Bob is holding the bottle by the neck. In the wide shot, he's holding it by the body.
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.
Other mistake: Bobby, Clovis and Celia Bradley find a large gold nugget in a mine. An assayer says gold is worth $15 an ounce and values the nugget at $87,425. That would mean it weighs 364 pounds, more than double the weight of the record-setting 173-pound gold nugget found in 1869 in Moliagul, Australia.
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: When the fireman falls from the engine passing over the deep gorge we hear him screaming. John Deakin examines the body and later explains that due to the lack of bleeding the man was already dead before he fell. (He theorizes he was killed and then pushed from the engine because he had discovered the 2 bodies of the missing officers in the woodpile).
Factual error: As well as the sergeant's stripes on his cuff, Sergeant O'Neil wears three pips on his epaulettes, which would indicate a much more senior rank and would not be worn together with the stripes.
Character mistake: Ryan's final diary entry says the US Cavalry fought against "French irregulars." The French lancers were actually regular troops.
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)
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: In this scene we see several Government Officials talking in a room. One of them, while talking, is playing a game. The game is to balance the lid of an ink bottle on the end of a ruler and over the ink bottle. When the ruler is flicked rapidly gravity would do the rest and the lid would fall into the ink bottle. Things don't work to plan and the lid falls on its side. In the next wide shot, the lid is right side up and a little distant from where it fell earlier.
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.