The nested dreams, only the guy in the hotel was floating when the van went off the bridge. Since the guys were floating around the hotel room, why weren't they floating in the next dream level. That was the only thing I found myself struggling with.
I feel it relatively clear that at the end, the top stops spinning and he is in fact, not in a dream. I feel that the "real" world in the film, is, for all intents and purposes actually the real world. I don't think half the film was a dream of his, or anything of the sort. I'm relatively certain we did see the top stop…