By the squirrel incident Rick scolds Morty that they can escape into another reality only a couple of times more - just like in Rick Potion #9 (We get three or four more of these, tops).
After creating the mutations, Rick says: "Boy, Morty, I really Cronenberged the world up, didn't I? You've got a whole planet of Cronenbergs walking around down there, Morty."
The haphazardly armored car Jerry drives after Rick's mutagen has overtaken the world resembles the armored parking shuttles from the final act of the Dawn of the Dead remake