Revealing mistake: In a shot of Gordon arriving at Brendam Docks, only half of his tender is visible.
Santa's Little Engine - S17-E18
Revealing mistake: At one point, the shading effect on Thomas' whistle is not rendered properly, so it appears silver instead of gold.
Revealing mistake: Each time when Thomas takes a shortcut, the points do not change.
Revealing mistake: Some of the team members of the football team are duplicated.
Revealing mistake: Max's wheels can be seen moving backwards when he is actually driving forwards. Also, both Max and Monty's steering and wheel speeds are out of sync with their movements. These events happen throughout the episode.
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.