Factual error: The gatling gun that Josey Wales uses had the options of a 40 round magazine, or a 104 round drum magazine. Neither Josey or the Red Legs ever bothered to reload the weapon. The gun would have been empty after the 10 barrels revolved at most 10 times. Josey alone shoots for a couple of minutes straight.
Factual error: The movie takes place in year 1865, when the U.S. Civil War ended. In the scene, where Lone Watie sneaks up on Josey and Moonlight sneaks up on Lone, the revolvers that both Native American actors are wielding, are equipped with Richards-Mason cartridge conversion kits, you can see the ejector-rod housing on the right side of the barrel. These conversions were not made until 1870's.Other characters as well use these conversion-revolvers throughout the movie.
Factual error: In the beginning when seen the Union attacking, the American flag has 50 stars not the 36 at the time of the war. The flag is incorrect.
Suggested correction: First, it's not a 50-star flag. There's a clear shot of the flag in one scene where you see it has 3 rows of 7-stars and 2 rows of 6-stars for 33-stars, although not in a pattern I'm familiar with. There's another shot where it's less clear, but you still only see 5 rows of stars and not 9 offset rows. Second, Nevada was the 36th state and didn't join until October 1864. The 36-star flag wouldn't have come out until July 4th, 1865, which was after the Civil War and wouldn't have been flown during the war.