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.
Visible crew/equipment: When Thomas says to Emily, "Give them back!", studio equipment is visible on the top-right corner of the screen.
Visible crew/equipment: When Henry puffs under the bridge, studio equipment can be seen in the top left corner.
Plot hole: When Duck and Diesel leave the shed, Diesel follows Duck instantly, but the tracks they are on both lead to the turntable. As they are on different tracks to each other, it would be impossible for Diesel to follow Duck that quickly as the turntable could only be set to one track at a time.
Other mistake: When Thomas is uncoupled from Annie and Clarabell he has Percy's face.
Character mistake: The narrator says, "some trucks were left behind", but only 1 truck was left behind.
Continuity mistake: When Murdoch returns to the shed in the last scene, Emily is there too, but in the last two shots, she disappears.
Revealing mistake: Salty is missing his rear lamp in the first shot at the docks and a hole is visible where it should be.
Revealing mistake: Dried-up glue is visible around Rusty's face during the line, "Right, we'll find one tomorrow."
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.
Other mistake: At the start Gordon's buffers are crooked.
Springtime for Diesel - S21-E1
Audio problem: Trevor has Stanley's whistle sound when he crosses the level crossing.
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.
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.
Lady Hatt's Birthday Party - S5-E4
Continuity mistake: When George drives into the ditch, the Fat Controller prematurely tips over, then tips over again in a closeup shot.
Saved You! - S12-E10
Continuity mistake: After he is rescued by Thomas, Toby's face changes size between shots.
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.
Other mistake: In some shots of Percy in the water, his boiler is chipped.
Revealing mistake: A wire can be seen between Rusty and his coach after the workmen have removed the ice from Skarloey.
Answer: He was in the water.