Visible crew/equipment: When Bill runs beside Boco, you can see a camera moving out of the shot. (Visible in HD full screen version).
Revealing mistake: At the end, when Thomas backs some coaches into the station, he starts moving after 3 seconds the camera starting rolling.
Revealing mistake: When Thomas passes the leveling crossing for a second time, the cars at the crossing have no drivers.
Revealing mistake: When Thomas goes back to the station to try again from the signal, when he starts, the steam is coming from the track and not from Thomas.
Revealing mistake: When Thomas passes a yard with a black car and a red car, you can see tyre marks on the ground from previous takes.
Revealing mistake: Just before Thomas goes over The Switch, his left eye is uneven and then when he crosses The Switch, it readjusts itself.
Other mistake: When the Fat Controller is talking to the crew, the buffers on the first coach in front of Thomas is crooked.
Visible crew/equipment: When the porter bangs the door, a light-stand is briefly reflected on the window of the door.
Revealing mistake: When Thomas leaves the sheds, his driver doesn't have a face.
Visible crew/equipment: When Henry is ill, one of the lights behind Henry is not one of the ones from outside, it's a studio light.
Other mistake: When Thomas is grumping, his lamp is dirty, even though he didn't do anything dirty yet.
Revealing mistake: At the beginning of the episode, the end of the set is visibly reflected of Gordon's smoke box in a close-up of Gordon.
Continuity mistake: When the engines are laughing at Thomas, Henry's eyes are wonky.
Factual error: At the beginning, the first shot of the episode, you can see cranes in the back of the station. They only have cranes at the harbor, not at stations.
Answer: Breakdown trains help the engines back on track.