Oh. I think I should warn you that the chamber we are about to pass into does not literally exist within our planet.
10 seconds sound clip from The Hitchhiker's Guide to the Galaxy (1981) - Episode 3 sitcom.
You can hear this line at 00:28:12.258 in the Blu-ray version of the TV Series.
Quote context
[...]
- Earthman, we are now deep in the heart of Magrathea.
- How do you know I'm an Earthman?
- These things will become clear to you. At least clearer than at the moment.
- It is simply the gateway to a vast tract of hyperspace.
- It may disturb you. It scares the willies out of me. Hold tight!
- Welcome to our factory floor. It Is where we make most of our planets, you see.
- You mean you're starting the whole thing up again now?
[...]