Other mistake: In some shots of Percy in the water, his boiler is chipped.
Other mistake: When Percy meets Thomas at Elsbridge Station, he has a water line across his boiler, even though the water only came up to his footplate.
Other mistake: After Toby breaks down, James pushes him directly to Knapford Station, not to the Works as it is said.
Thomas, Percy and the Dragon - S3-E7
Revealing mistake: When Thomas asks Percy about the guard leaving the light on, Thomas' right eye jitters.
Thomas, Percy and the Dragon - S3-E7
Visible crew/equipment: When James passes Percy, two studio lights and a crew member are reflected in James' paint.
Visible crew/equipment: In the scene where James pulls up beside Gordon, studio equipment is visible in the top portion of the screen.
Visible crew/equipment: When the trucks are pushing Toby, in one shot you can see a crew member's hand pushing the trucks, then it vanishes.
Edward, Trevor and the Really Useful Party - S3-E16
Visible crew/equipment: When Bertie is talking to Trevor, in one shot of Trevor, studio equipment is visible in the top left hand corner.
Revealing mistake: While the passengers are evacuating the station, the platform moves, a pillar in the background moves, and putty can be seen on the platform (stains of it) and on some passengers' feet.
Other mistake: When Bill and Ben are pushing each other, Bill has no eyes, Bill and Ben's faces are slanted at the bottom, and Ben's cylinder pipe is crooked along with a tack above Bill's face seen.
Other mistake: When Oliver leaves for the Works after his accident, Toad's eyebrows are missing.
Thomas and Percy's Christmas Adventure - S3-E26
Audio problem: When this episode was re-narrated in the US, it was changed to an episode about Thanksgiving. This caused a scene to get cut, which messed up the dubbing track, making half of the episode out of sync. (00:03:00)
Answer: Breakdown trains help the engines back on track.