Audio problem: In the US version (Rusty Helps Peter Sam), Peter Sam has a different whistle sound after the trucks hit him. And throughout the episode, a lot of music and sound effects are missing.
Audio problem: Gordon had Duck's whistle sound and James had a different whistle sound in almost every Season 4 episode they appeared in.
Audio problem: Thomas has James' whistle sound when he passes Sir Handel at the beginning.
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.
Answer: Breakdown trains help the engines back on track.