Continuity mistake: In a close up of Thomas when Gordon is pulling him, Thomas is not coupled up to Gordon's train.
Thomas Puts the Brakes On - S12-E17
Continuity mistake: Thomas has a brake van when he arrives at the bridge. When Stanley, Thomas, Murdoch, and Rocky start looking for the bricks, the brake van disappears.
Thomas Puts the Brakes On - S12-E17
Revealing mistake: In the very last shot of the episode, Thomas and Stanley are faceless.
Revealing mistake: In a close up of Gordon after Rocky clears the tracks, Gordon has wonky eyes.
Revealing mistake: When Gordon is being pulled from the pond, in the close up scene of Gordon reversing up the sleeper bed, the front of his buffer beam/running board catches on the upright stake to the right hand side of the worker figure, pulling it back before it rights itself. (easier to see on widescreen version). (00:04:10)
Audio problem: Mavis has Derek's horn sound.
Continuity mistake: The narrator says that Dart had never seen the logging locos before, but he saw them 3 episodes ago.
Santa's Little Engine - S17-E18
Continuity mistake: The sleigh leaves tracks in the snow behind when it slides down the hill. When Thomas races towards the sleigh, the Snow Tracks disappear.
Audio problem: At the beginning, Henry has Gordon's whistle sound. And when Spencer's driver rings the bell after stopping at the countryside, the bell is heard, but cannot be seen.
Other mistake: Thomas has two side rods when he crashes into the pile of dirt. The duplicated side rod moves even though Thomas' brakes are applied.
Character mistake: At the beginning, the narrator refers to the Quarry as the Smelters.
Other mistake: Henry was supposed to take Emily's trucks to the Coaling Plant, but he takes them to Knapford Yards instead. The narrator also refers to Knapford Yards as the Coaling Plant.
Continuity mistake: When Salty gets blocked by the trucks, his face increases in size.
Deliberate mistake: In the PBS airings in the U.S. of "Tuneful Toots" and "Duncan and the Old Mine", Rusty is referred to as a female rather than a male.
Continuity mistake: The mail van moves without a driver.
Audio problem: Douglas has Donald's whistle sound when he passes Murdoch.
Plot hole: When Gordon crashes into the goods train, it is not being pulled by an engine. So why is it just sitting on the mainline and not on a siding?
Audio problem: Gordon has a different whistle sound when he cuts in front of James at the water tower.
Character mistake: The narrator refers to Gordon as "Gordon's engine."
Answer: Butch the breakdown truck must have pulled Gordon's tender all the way up the rails so the breakdown train can reach it and also Butch helped to get Gordon close to the winch.