Locutus of Bored wrote:
The top was clearly undergoing precession, meaning it will inevitably fall, and the kids at the end were meant to be around two years older and were played by different actors. Seems pretty clear that he was in the real world to me.
The kids' age is another situation that keeps things ambiguous. True, it could indicate that it's reality. But, Cobb could easily dream, in this his perfect dream, that they are two years older, as they would be in reality.