Thomas and the Missing Christmas Tree - S2-E26
Visible crew/equipment: In the scene of Donald and Douglas going out of the yard, a camera tripod can be seen in the top left corner.
Wrong Road - S2-E22
Revealing mistake: When Gordon says, "I am Gordon! Stop! Stop!", his eyes are wonky.
Other mistake: The Breakdown Train to the left, in the opening scene, is derailed.
Visible crew/equipment: The reflection of a crew member's face is visible in the window of Edward's cab when his driver cheers him on.
Wrong Road - S2-E22
Revealing mistake: Wires to power the lamps are very visible on Gordon's and Edward's buffers, and bulbs are also sticking out from both their lamps.
Trivia: When Bill and Ben find Boco, there's a soup can on the left of the screen, dressed to be part of the set like a large oil drum or similar.
Visible crew/equipment: When Bill and Ben go by a level crossing, the top of the set is visible.
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.