Thomas, Percy and the Coal - S2-E1
Revealing mistake: In some shots of Thomas and Percy, both engines have wonky eyes.
Thomas, Percy and the Coal - S2-E1
Revealing mistake: When Toby pulls Annie and Clarabel, the latter coach has a loose roof.
Thomas, Percy and the Coal - S2-E1
Continuity mistake: When Thomas is being covered in coal, he is dirty in some shots, but in other shots he is clean.
Revealing mistake: Each time when Thomas takes a shortcut, the points do not change.
Factual error: When Bertie finds Thomas derailed, Bertie is on the wrong side of the road. The UK drives on the left. Also, Thomas runs under North American directional rules at the beginning and end of the episode.
Character mistake: UK Only: When Thomas comes back to Annie and Clarabel, he calls the latter "Carabel."
Continuity mistake: Gordon's connecting rods change position after he pulls Thomas out of the mine.
Character mistake: Black smoke comes out of Thomas' funnel 50 seconds before the narrator says so. (00:03:40)
Character mistake: In the trivia game on the "On Site With Thomas" DVD, Monty's name is misspelled as "Monte."
Factual error: In the "Steamie or Diesel" game on the "All Aboard with the Steam Team" DVD, Spencer is incorrectly called a diesel even though he is a steamie. Whenever you get the wrong button, Spencer says he actually has a horn instead of a whistle and even says he is a diesel engine.
Wrong Road - S2-E22
Revealing mistake: When Gordon says, "I am Gordon! Stop! Stop!", his eyes are wonky.
Visible crew/equipment: When Diesel is on the turntable, camera equipment is reflected in the windows for several moments. (00:02:00 - 00:10:00)
Visible crew/equipment: When Bill and Ben are shunting, we can see hands. (00:02:00 - 00:10:00)
Thomas and the Billboard - S12-E1
Other mistake: In the opening scene when Edward and Henry can be seen going into Knapford, Henry is wearing Gordon's face mask.
Other mistake: When James crashes into the tar wagons, Sticky Tac can be seen on his tender.
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)
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.
Audio problem: In the extended Season 19 version of "Engine Roll Call," Henry's whistle sound is out of place as it can be heard during Emily's part of the song. Also, Henry is not mentioned in the Season 22 version of the song, but his whistle sound can still be heard.
Thomas, Percy and the Squeak - S6-E21
Continuity mistake: When Percy arrives at Brendam, his steam platform is visible and some of the steam from his funnel disappears, indicating a film cut.
Thomas, Percy and the Squeak - S6-E21
Other mistake: When Alicia the mouse is inside Clarabel, she is missing her forepaws.
Answer: He was in the water.