The West vs. Colonel MacKenzie - S9-E1
Other mistake: In the beginning of 2-19 "The Drifter" the Virginian says it had been 7 years since he had come to the Shiloh. But in this episode he tells him that he and Trampas had been there 9 years. Doesn't add up. He had to be there before Trampas, longer than 9 years.
Continuity mistake: The red draperies framing Hannah's train-window flashback do not even vaguely resemble the drapes seen on the same window in every other shot aboard the train.
Continuity mistake: After the fight at the train depot, Colonel MacKenzie's rumpled ascot straightens and reties itself between shots.