At one point in the film Sandy wonders if they are going in circles, referring to a piece of a mesa resembling a cathedral. The two then halt the wagon train and then scout on ahead. Later, after the Marshall and his deputies stop the train, the same mesa can be seen in the background as the wagon train travels in the opposite direction. This shot was made from the same exact camera position in both scenes. Later, when getting the wagons over the wash-out and Travis throws the gun away, the exact same background is seen once again, and again from the same exact camera angle.
After Denver throws the bucket of water on Travis and he falls in the dirt, his arms and back are covered in dirt, in the next shot there is hardly any dirt on him, and he did not have time to brush it off.
In the beginning of the film, when Travis on the horse talks to the marshal, he folds his right leg leaning it on the saddle horn. In the next shot he is with his right leg hanging unfolded.
When the marshal mounts the horse and Sandy whistles, he is sitting on the fence, on the right side of Travis. Soon after, when the Mormons arrive, Sandy is sitting on the left side of Travis
Prudence arrives after Wiggs and Adam, and stands behind them, in front of Sandy on the fence. Between shots she appears near Sandy, with her back to him.
In the middle of the film the pioneers have a dance on a dozen wooden planks laid down in the middle of the camp. Wagon trains would not have any need for milled lumber. Nor would they have tolerated carrying such useless extra weight.
If the opening song is accurate, the movie takes place in 1849. The opening murder shows a lever-action rifle, which didn't exist for more than 10 more years.
A Golden Retriever is shown in close-up during the credits sequence. Goldens were originally bred in Scotland beginning in the 1860s, and were not registered in America until 1894. It's "possible' that a Golden could have been accompanying the wagon train, but very unlikely.
As the camera pans along the wagon train moving through Moab, Utah, it passes by a boulder, on which you see the shadows of the camera crew and director John Ford.
While the peaceful Mormon homesteaders may not have been carrying sidearms, that they would also not have rifles and shotguns (for hunting and protection from animals) seems unlikely. Certainly 19th century Mormons didn't have an aversion to firearms - one of the greatest gun designers in history, John M. Browning, was a practicing Mormon.
When the Navajo woman accuses one of Clegg's gang of improper advances, she starts screaming in another language that sounds suspiciously like Spanish not Navajo. The actress was a Mexican American actress.