Hey there, Javier!
I friggin' LOVE Rick and Morty and I took a look at a few pages of your script.
I think you captured the voices of the characters very well. So far I'm enjoying the story.
There is a technical error that's a simple fix. Its on page one.
You have the slugline:
INT. ALIEN BAR - NIGHT
And then you go straight to a character line and dialogue.
Basic rule, always have an action break between sluglines and dialogue. Again, this is an easy fix, just put a character description of the BARMAN first.
Anyways, I'm going to keep reading it later on but so far, good job!