Revealing mistake: In a close up of Percy's driver, he is in Henry's cab.
Revealing mistake: When Percy is at the "backing" signal, his cylinder is sagging.
Thomas the Tank Engine & Friends (1984)
2 revealing mistakes in Percy and the Signal - chronological order
Starring: Alec Baldwin, Michael Brandon, Ben Small, Martin Sherman, Michael Angelis
Continuity mistake: When Bulgy is driving on the road next to the rails, Thomas can be seen pulling a train instead of being repaired at the foundry.
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.