We can get away with this because the LEM is designed only for flight in outer space.
6 seconds sound clip from the Apollo 13 movie soundboard.
You can hear this line at 00:48:18 in the Blu-ray version of the movie.
Quote context
[...]
- Fred Haise and I will float through this access tunnel into the lunar module, leaving...
- EECOM, that stir's gonna be on both H2 and both O2 tanks, is that correct?
- The spacecraft will remain connected.
- We can get away with this because the LEM is designed only for flight in outer space.
- Fred Haise, Renaissance man.
- Okay. We'll head back up the tunnel now and back into the Odyssey.
- All right, we've returned to the command...
- Gotcha!
[...]