Audio problem: In the first shot, Duck's chuffing sound doesn't match his speed.
Revealing mistake: Duck's footplate clips through the platform at Knapford at the beginning.
Duck and the Slip Coaches - S18-E8
Audio problem: At the beginning, Edward has Thomas' whistle sound.
Revealing mistake: Some trucks are completely Off the Rails at the clay pits.
Continuity mistake: Throughout the episode, rust stains disappear and reappear on Duncan's front buffers.
Samson at Your Service - S18-E24
Revealing mistake: James is shifted on his body when Samson leaves him.
Answer: Breakdown trains help the engines back on track.