Continuity: After the Baxter/Rojo dinner, the background changes from nightime to daytime at the cemetery, then back to nightime again when Clint kidnaps Mirasol.

Factual error: When the Rojos steals the gold from the Mexican soldiers, one of them uses an automatic machine gun to scythe them down. While it has been poorly disguised as a gattling gun, it is clearly a 'true' automatic machine gun, probably either a Vickers or a Browning. Such guns did not exist at the time the movie was set, not long after the Civil War (The Good, The Bad, And The Ugly, set during that war, was actually a prequel).

Continuity: In the opening scene, when 'Joe' is helping himself from the well, the angle to the sun varies from the left side to almost vertically.