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.
Answer: He was in the water.