They didn't cram anything, Devon. Episode 13 was as eventful as any other episode. I assume they had most episodes filmed when they were told that the plug was being pulled. Episode 13 played out as if it was part of a full 22 episode season, but since Vanished wasn't extended past a 13 episode run, they had to tack on the ending to give it a bit of closure.
I'd love to have seen them given an extra 3 or 4 episodes to finish the story properly (like Surface last year).