5. Cobb Is Still Asleep In Mombasa
When assembling his team, Cobb heads to Mombasa to recruit Eaems and find a serum powerful enough to sustain the three dream levels. He is taken to Yusef, who shows him a room full of people who take a concentrated dose just so they can dream at all. One theory is that not only is Cobb dreaming at the end, but that his doing so from when he tries the serum. We know Cobb is unable to dream properly due to his mental projection of Mal haunting him, so he is unlikely to distinguish between reality and dream. The fact that everything goes so well for him even though theres the added complication of Fischers security, the plan goes off very well and he not only beats him demons, but gets to return to his family. The key evidence for this theory is the totem. We only ever see it topple once (in Japan before we even understand its significance) and that is before Mombasa. Directly after the experience we see Cobb fail to test, dropping the top (an attempt by the dreamer to hide the truth from him perhaps?). We never see him check again, so theres no actual evidence refuting this theory, but the fact no reference is ever made again, it is unlikely. Still, its an exciting explanation for why the top wouldnt topple at the end and is completely separate from the Mal plot; instead, it offers Cobb a way in which to deal with him past.