The film takes place in the 1840s based on the 26 star flag (1837-1845). Coleman (John Wayne) carries a Remington New Model Army revolver, patented in 1858 and manufactured in the 1860s.
The film takes place in the 1840s based on the 26 star flag (1837-1845). Many of the settlers use Springfield Model 1873 "trapdoor" rifles. This was common in Hollywood because the 1873 was based on the 1861 rifled musket, which closed a continuous line of muskets going back to 1795, so it could easily stand in for a muzzle loading musket to the untrained eye.
(at around 1hr 23 mins) Motor vehicles are moving in the far distance (top left of frame).