As you noted, large portions of this episode are improv’d by Justin Roiland just rambling in the recording booth. I think there’s videos of him getting drunk and doing this kind of stuff.
There’s an episode like this in every season, though it won’t always be interdimensional cable, it’ll be something else but with similar kind of random ideas and random scenes (sometimes more scripted). It’s some fan favorites because they’re usually so random and weird but funny, but not worth a full episode on their own.