I'm a week late, and kind of glad I waited until today to watch it so I don't have to wait as long for tonight's.
It's strange that apparently I'm the only one who had this theory:
Elliot actually looks like Christian Slater. That's him. He had a family and everything and then lost his shit and erased it all; both from his mind and public record. We've all thought they were the same person all season, but in this theory it's not that Elliot has multi-personality with a personality that looks like his father, it's that he has a multiple personality of maybe his son grown up (or just some random kid).
The only part that wouldn't make much sense is all the stuff with the blonde girl. Christian Slater would be way too old to be hanging out with her, even if it was his sister's best friend.
Either way, this show is awesome. It's like a combination of the best parts of Fight Club, Memento, and LOST.