Originally, the hanging scene was shot as a POV flashback. However, to clarify the narrative, it became the opening scene for the film, and Tim Russ was composited into it using green screen effects.
If you notice in the night flashback, Krug has a bowler hat. However, by the time he transforms into a gunslinger, he has a beat up duster hat. The explanation is that Coyote Gus took Krug's hat during the night raid and left his own, which Krug picks up from the wagon area after burying his wife. So, in the shootout scene, they have switched hats! Krug recognizes his hat, which you can subtly see in his look when he's sizing up the bandits.