Revealing mistake: When Thomas leaves the sheds, his driver doesn't have a face.
Revealing mistake: At the beginning of the episode, the end of the set is visibly reflected of Gordon's smoke box in a close-up of Gordon.
Edward, Gordon and Henry - S1-E4
Revealing mistake: When Gordon passes a signal, the track under him wobbles.
Revealing mistake: When Gordon puffs into the ditch his face looks wonky and wires are visibly attached to his cab.
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.