Thomas and the Missing Christmas Tree - S2-E26
Other mistake: In the shot of Donald, (or Douglas) Gordon and Henry, Donald has Edward's face.
Thomas Comes to Breakfast - S2-E18
Other mistake: The narrator said Thomas was feeling conceited, but Thomas had his sad face mask on instead.
Other mistake: When Bill and Ben find Boco, there's a soup can on the left of the screen.
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.