More Questions *spoilers*
Okay, this is following up on the other Questions post. I agree that there were a lot of hints to suggest that the whole thing was going on his head, and I was surprised and a little disappointed at the total lack of a twist at the end. Firstly, as the other person said, it was a little strange that when he awoke, he already knew:
a) He'd been cryogenically frozen.
b) It was the future.
c) He was going to be getting a lethal injection.
As someone else said, it's possible that while in a coma, he heard people discussing the operation, and perhaps he even made up the memory of going to sign up for a cryogenics study to go along with that. But what about knowing he was going to get an injection? Did he overhear something about that when they first brought him back? That seems like a bit of a stretch.
Beyond that, there were other strange things. Like, where did the electric guitar and the walkman come from? Was I the only one who thought it was really strange that they just happened to be there? I mean, the orderly apparently brought in the guitar (why?), but the walkman just appeared in one of the last scenes. Maybe it was in his jacket when he was first injured, and they kept the jacket while he was frozen? I dunno, it's pretty strange.
Also, why did they go to the trouble of trying to convince him it was 1999, and that he was basically crazy? I mean, okay maybe I buy that they needed to wake him up and assess his physical health before operating, but why should they care about his mental state? And what effect was pretending it was 1999 supposed to have on his mental state?
Anyway, I think if it had all been a delusion, it wouldn't have been a particularly original ending, but at least it would have made a more coherent story.