Continuity mistake: Because of the production order, Murdoch appears at the sheds, but his introduction is 2 episodes later, in "Peace and Quiet." Spencer also appears at the sheds, but his introduction is 8 episodes later, in "Gordon and Spencer."
Continuity mistake: The fisherman appears out of nowhere when he tells Thomas to enjoy the smell of the fish.
Continuity mistake: When Arthur is waiting for the fat controller to pick him to run the new line, in a wide shot of the sheds, Henry is very close to him, but in a close up of Aurthur, Henry has vanished and Gordon appears one line beside him.
Continuity mistake: Thomas was pushing 4 trucks and a brake van, but when the trucks are laughing at Thomas, there are 2 trucks and a brake van. A truck also gains a face.
Answer: Breakdown trains help the engines back on track.