When Juan answers the last call at the 'Juan de los Muertos' phone service, he says something like: "Quien? ...no. Eso lo deben arreglar entre ustedes."
I didn't get that joke.
Also, what was the 'cosa esta que vino después' (del periodo especial) ?
The special period you can just google to learn about. Look it up on wikipedia, it is nicely explained there. It has to do with what happened in Cuba in the 90s after the Soviet Union dissolved.
As for the other line ... if that is the scene I am thinking of, I think subtitles I saw translated the line as something like "you'll have to take care of that one yourself". The only thing I can think of is that maybe someone was asking him to get rid of Castro?
Yeah, they never stated it outright, but it definitely had the feel that he was being asked to clean up after something very political. I'm sure most people would immediately think it was Castro, that's certainly the first thing that crossed my mind.
As for what "came after" the special period, it's a joke about the screwed up situation even after "normalcy" supposedly returns, as if it's still a crisis, because it is, the island is in constant crisis so if it's not one thing, it's another.
I'm so ugly...that's ok 'cause so are you.
I had the impression the phone call referred to get rid of Castro.
Maybe it was just a soldier type person, but near the end when they are surrounded by zombies I had the impression that one of them was dressed like Fidel Castro, implying that he was amongst the undead ?