Factual error: Though extremely modest by today's standards, the dress worn by Clara at the hoedown shows far too much cleavage for the time. No schoolteacher would ever wear a dress like that in the 1880s.
Factual error: When Glass saves the Indian girl from the Frenchmen the flintlock pistol he gets off the Frenchman fires multiple times without reload, as it does later while being chased by the Indians.
Factual error: During the gun battle, Gary Cooper runs behind a building that has an air-conditioner or swamp cooler installed in a second-floor window. (01:17:30)
Factual error: The type of book that Eli is protecting would actually be just a fragment. The complete Bible, in braille, occupies as many as 18 volumes.
Factual error: After the birth of the baby, James Stewart and "Doc" Witherspoon are discussing the course of the war. "Doc" relates that he has always lived in Virginia and that his son died at Gettysburg at Little Round Top. No Virginia regiments fought at Little Round Top - only Alabama, Texas, Georgia, and Arkansas regiments.
Factual error: Dr Schultz pays with 12 $1000 bills, but $1000 bills were not created until 1861, after the time period of this movie.
Factual error: After the first encounter with the Apaches, the covered wagon is headed to the Fort at full speed. The camera pans to the Apaches on the ridge and you can see a truck driving at the bottom right corner. (00:32:00)
Factual error: As Preacher and Hull ride out of town for first time, Hull offers "3 hots and a cot." Earliest reference of this term is in the 1930's.
Factual error: The evil man request 100,000 pieces of gold for ransom. Each gold piece looks to be about 10 ounces, and 100,000 of those would make the entire thing weigh about 31 tons, but 2 guys are carrying it around in a little chest throughout the movie.
Factual error: In the train scene near the start there are vapor trails from modern day jet aircraft in the sky above. (00:06:15)
Factual error: Towards the end when the cavalry uncovers the American flag, it has 50 stars.
Factual error: So the Civil War ends, and the colonel heads for Texas. It must have taken close to a decade to arrive there, for when he rides into Blackthorne, Texas, he's packing a Model 1873 Colt, and a Model 1873 Winchester.
Factual error: Near the end of the film Butch is complaining about the living conditions they have to endure - jungles, swamps, snakes, night work - and Sundance sarcastically retorts "Bitch, bitch, bitch!" In 1908 the term meant just what it literally means: "Female dog." It did not adopt its current meaning of "complain" until much later. At the time the film is set - outside the context of "female dog" - it was considered to be a serious obscenity, and it would not have been used to describe something as ordinary as someone moaning about his living conditions.
Factual error: John Wayne and James Caan are in the gunsmiths shop, and behind the gunsmith on the shelf are some products, one of these products is Bugler tobacco. Bugler tobacco was introduced in the United States in 1932. (01:00:00 - 01:02:00)
Factual error: In the final gunfight in Hasting's store, John Elder fires his six-shooting Colt to a total of thirteen or fourteen times, without requiring - or doing any - reloading whatsoever.
Factual error: In the scene just before the fight at the O.K. Corral, Wyatt is talking to his brothers and Doc on the porch of the town marshal's office. There is an American flag flying behind him with 50 stars on it when in fact there were only 38 stars on the flag in 1881.
Factual error: When the riders are watching the wagon train, in the background you can see a communication tower with conical speakers.
Factual error: Outside the Territory Hotel, during the storm, and once earlier in the movie, the taxi cabs are shown with the modern "flip over" vacancy/hired signs that were not used then.
Factual error: The El Paso newspaper is dated Monday June 15 1872. June 15 1872 was a Saturday. (00:48:14)
Factual error: The movie takes place in the early 1850's, referencing the rumor of gold in California. The girl, while rummaging through the wagon, comes across a pair of boots with zippers up the sides, zippers that wouldn't be invented for another 50 years.