Thomas' Christmas Party - S1-E26
Trivia: At the end, the podium on which The Fat Controller is standing, is made of LEGO bricks.
James and the Red Balloon - S6-E15
Continuity mistake: When Percy arrives at the docks, he is carrying some freight cars. But when Thomas leaves the cars Percy was carrying disappear.
Visible crew/equipment: In the scene where James pulls up beside Gordon, studio equipment is visible in the top portion of the screen.
Continuity mistake: When Murdoch returns to the shed in the last scene, Emily is there too, but in the last two shots, she disappears.
Continuity mistake: After Stepney's driver tells Stepney to speed up, Caroline is nowhere to be seen.
Visible crew/equipment: When the Fireflies form the engine, the end of the set is visible in the distance.
Continuity mistake: When James passes Edward at Knapford, Edward's train does not have a brake van. But two shots later, it does.
The Sad Story of Henry - S1-E3
Revealing mistake: When the passengers try to pull Henry out of the tunnel, they have putty on their feet. Sir Topham Hatt's hand is also purple.
Revealing mistake: In a shot of 2 vans singing "Pop Goes Old Ollie" you can see a spider crawling on the right side of the left van in the screen.
Continuity mistake: The sign says: "Danger - engines must not pass this board." When Thomas passes it, "board" is replaced with "point."
Thomas and the Breakdown Train - S1-E7
Revealing mistake: In the scene of James' wheels sparking while passing Tidmouth Sheds, a metal rod is igniting the sparks from his wheels.
Visible crew/equipment: As Henry crashes into the goods train, a crew member's hand can be seen pushing him, at the left side of the screen.
Thomas and the Missing Christmas Tree - S2-E26
Visible crew/equipment: In the scene of Donald and Douglas going out of the yard, a camera tripod can be seen in the top left corner.
Saved You! - S12-E10
Continuity mistake: After he is rescued by Thomas, Toby's face changes size between shots.
Santa's Little Engine - S17-E18
Revealing mistake: At one point, the shading effect on Thomas' whistle is not rendered properly, so it appears silver instead of gold.
Continuity mistake: Throughout the episode, rust stains disappear and reappear on Duncan's front buffers.
Wrong Road - S2-E22
Revealing mistake: When Gordon says, "I am Gordon! Stop! Stop!", his eyes are wonky.
Visible crew/equipment: In the shot of Thomas rolling backwards onto the turntable, look left very carefully, and you'll see a camera tripod visible. Fullscreen version only.
Revealing mistake: When the elephant is loaded into the truck, the tracks abruptly end behind Charlie.
Thomas' Christmas Party - S1-E26
Visible crew/equipment: When Toby puffs by at the beginning, a camera shadow is visible on the bottom right corner.
Answer: He was in the water.