Wrong Road - S2-E22
Revealing mistake: When Gordon says, "I am Gordon! Stop! Stop!", his eyes are wonky.
Wrong Road - S2-E22
Revealing mistake: Wires to power the lamps are very visible on Gordon's and Edward's buffers, and bulbs are also sticking out from both their lamps.
Wrong Road - S2-E22
Revealing mistake: When Edward crosses the viaduct, the last coach of his train does not have lighting.
Answer: Breakdown trains help the engines back on track.