Time of year this takes place?
Little Bill beats up English Bob on or about the 4th of July. Not long after, it seems, Will Munny and company arrive. Soon thereafter, he receives a severe beating. While recovering, there is a nice scene between him and the prostitute who was mutilated. However, it's snowy around the area. What's more, when Will recovers and sets his mind on revenge, it is raining again as it was earlier in the movie.
It seems the events of the movie should only occur only, at the most, a few weeks. Does it snow in the low country in Wyoming in July? Or is this a simple artistic license so the movie can have a nice scene in the snow?