The War Comes to Washoe - S4-E7
Other mistake: In early evening, Hoss and Adam discover the body of a man who had been shot with an arrow and killed. Even though it is still very bright sunlight, Adam lights a match and holds it close to the man's face so he can see who it is, then lights another match so he can read a letter that was in the man's coat pocket.
Other mistake: At night, Adam goes to visit a man whose brother has been shot and killed. After the man lights a lantern on the table to Adam's right, Adam's shadow is to his right and not to his left as it should be.