Bye George - S5-E7
Audio problem: Gordon has Duck's whistle sound before he crashes into the truck.
Factual error: The dam was built concaved from the water it holds back, but it would have been built convex in order to do so.
Visible crew/equipment: When Henry puffs under the bridge, studio equipment can be seen in the top left corner.
Visible crew/equipment: When Stepney puffs through the fog after dropping off the stone loads, studio equipment can be seen in the top left corner of the screen.
Continuity mistake: When Toby comes up to the junction, the lever to the points isn't actually there. It is only seen in this episode in the shot showing where his fireman switches them.
Thomas, Percy and Old Slow Coach - S5-E16
Other mistake: When James cries for help, his eyes are wonky.
Continuity mistake: After Toad avoids James, a works coach moves from in front of the points to behind the points.
Revealing mistake: The rails to the buffers are broken as Toad leaves the siding.
Revealing mistake: When Toad switches lines to avoid Gordon, the track ends in bushes.
Visible crew/equipment: When Toad falls into the pond, in the shot from his point of view, studio equipment can be seen in the top left corner.
Visible crew/equipment: When the Fireflies form the engine, the end of the set is visible in the distance.
Revealing mistake: A wire can be seen between Rusty and his coach after the workmen have removed the ice from Skarloey.
Revealing mistake: The waves hitting the ship are obviously being sprayed by a hose.
Continuity mistake: Henry pushes Percy onto the coal tipper twice.
Plot hole: Percy was blamed for being on the coal tipper when it was Arry, Bert, and Henry's fault. None of the three got consequences. Also, why would the workmen tether Percy or even activate the coal tipper when they knew he was an engine?
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.
Gordon Takes a Tumble - S6-E17
Character mistake: When the narrator says "but the signalman had accidentally left the points switched to the branch line" there is no switch, it's just a bend.
Gordon Takes a Tumble - S6-E17
Continuity mistake: The amount of trucks Gordon is pulling repeatedly change.
Audio problem: Mavis has Derek's horn sound.
Thomas, Percy and the Squeak - S6-E21
Other mistake: When Thomas sees Percy at the washdown, Gordon's front and rear bogie wheels are derailed.
Answer: He was in the water.