But there must be some mistake.
4 seconds sound clip from the The Nightmare Before Christmas (1993) movie soundboard.
You can hear this line at 00:46:48 in the Blu-ray version of the movie.
Quote context
[...]
- Surprised, aren't you? I knew you would be.
- You don't need to have another worry about Christmas this year.
- What?
- Consider this a vacation, Sandy. A reward. It's your turn to take it easy.
- But there must be some mistake.
- Of course! That's what I'm missing. Thanks.
[...]