Audio problem: Mavis has Derek's horn sound.
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.
Audio problem: Douglas has Donald's whistle sound when he passes Murdoch.
Audio problem: Gordon has a different whistle sound when he cuts in front of James at the water tower.
Audio problem: Gordon had Duck's whistle sound and James had a different whistle sound in almost every Season 4 episode they appeared in.
Rosie's Funfair Special - S12-E3
Audio problem: In the US version, Stepney says "Oh my!", but he doesn't sound shocked and his mouth doesn't match the words. In both US and UK versions: he blows his whistle multiple times, but it only emits steam once, and it sounds like Thomas' at a slightly higher pitch.
Gordon Takes a Shortcut - S12-E15
Audio problem: Stanley has a different whistle sound. His original whistle sound is essentially Thomas' at a lower pitch, but in this episode, it is Thomas' at a higher pitch.
Audio problem: When Oliver arrives at the station, he has Percy's whistle sound.
Audio problem: At the beginning of the episode, Salty has Diesel's horn sound.
Audio problem: Thomas has James' whistle sound when he passes Sir Handel at the beginning.
Audio problem: When Thomas and Butch deliver Rosie's wheel, her whistle sound is at a higher pitch.
Audio problem: Stepney's whistle sound changes throughout the entire episode. And in the UK and other versions (excluding US), Gordon, Duck, and Douglas have the same whistle sound.
Bowled Out - S4-E18
Audio problem: When James leaves Crovan's Gate, he has Smudger's whistle sound.
Audio problem: When Den and Dart bully Flynn, their voices are swapped.
Thomas' Christmas Party - S1-E26
Audio problem: (Only in the George Carlin narrated American version) At the end of the episode, when the engines are singing "We wish you a merry Christmas", you can briefly hear Ringo Starr's original narration.
Audio problem: Before Emily goes into the duck pond, her brakes are heard screeching but her wheels are still moving.
Audio problem: When Gordon backing down to the bottom of the hill, you can hear brakes screeching, but Gordon's wheels are still moving.
The Runaway - S2-E10
Audio problem: When Thomas is tired and approaching the station, he is moving pretty slow, but the sound of Thomas' wheels moving is like he's going pretty fast.
Audio problem: In the first shot, Duck's chuffing sound doesn't match his speed.
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.