There is a way. But it's impossible.
6 seconds sound clip from the Supergirl (1984) movie soundboard.
You can hear this line at 01:42:16 in the Blu-ray version of the movie.
Quote context
[...]
- I'm only laughing at myself. For you, I weep.
- Is this train a way out of here?
- There is no way out of here. That is the point of the Phantom Zone.
- But, there's always a way out. If there's a way in, there's a way out.
- There is a way. But it's impossible.
- Why? (2)
- No, it wouldn't work. You'd be swept into a singularity if it didn't work. No.
- Forget I mentioned it. Have a squirt instead.
- Then, please. At least teach me how.
[...]