Continuity mistake: In a close up of Thomas when Gordon is pulling him, Thomas is not coupled up to Gordon's train.
Continuity mistake: When Gordon approaches the station, in the two previous shots, the background changes from a close up of Gordon to a wide shot of Thomas and Gordon.
Continuity mistake: When Gordon says "Yes, I will" the background disappears between shots.
Continuity mistake: In the shot of Thomas stopping inside Knapford with his coaches, Henry is in his new shape.
Answer: Butch the breakdown truck must have pulled Gordon's tender all the way up the rails so the breakdown train can reach it and also Butch helped to get Gordon close to the winch.