That was an awesome episode, and an awesome ending to an awesome show.
I kind of called that ending, though. They HAD to die, or else, due to the Butterfly Effect, SOMETHING would have changed. The only way they could have not died is to have secluded themselves in some lead-lined vault to escape the Apocalypse and then been out in the desert or something to not have any interaction with anyone else whatsoever. I'm glad you guys made a Stable Time Loop.
Though, they were screwed in any case. Don't go in? Universe blows up. Go in and change something? Galaxy blows up. Go in and don't change anything? Apocalypse still happens and world (kind of) blows up. Something they're in always blows up in any case.
Though, one thing I did not expect was Hickey's face being messed up BEFORE the Apocalypse. I always thought that's something that happened when the bomb went off.
Edit: Also, before I checked the status bar at the bottom showing where the movie was, I was expecting the end to be when Steve and Cuddles were sitting there drinking on the lawn. I wonder how many other people did a double-take at the status bar like I did.