Other mistake: Oliver's arm is too tall to fit under the bridge.
Other mistake: Thomas has two side rods when he crashes into the pile of dirt. The duplicated side rod moves even though Thomas' brakes are applied.
Thomas the Tank Engine & Friends (1984)
2 other mistakes in Mucking About
Starring: Alec Baldwin, Michael Brandon, Ben Small, Martin Sherman, Michael Angelis
Continuity mistake: Despite Henry's issue from "Coal" in Season 1 being resolved after the crash in "The Flying Kipper", also in Season 1, Henry needed special coal again from "Thomas and the Magic Railroad" until Season 16.
Duke: Excuse me. Are you a vandal? Driver told me vandals smash and break things.
More trivia for Thomas the Tank Engine & Friends
Question: Why was Henry put on a barge instead of being taken to the works?
Answer: He was in the water.