Thomas and the Billboard - S12-E1
Revealing mistake: At the beginning of the episode, Henry has Gordon's face.
Thomas and the Billboard - S12-E1
Other mistake: In the opening scene when Edward and Henry can be seen going into Knapford, Henry is wearing Gordon's face mask.
Thomas and the Billboard - S12-E1
Visible crew/equipment: When Percy leaves the station, a camera shadow is visible.
Thomas and the Billboard - S12-E1
Visible crew/equipment: At the very start of the episode, a stage light is reflected off Gordon's coaches.
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.