At the end when the top is spinning and looks like it is about to topple, but doesn't quite. Well at the end he is NOT in a dream because the top is not his totem. The top was his wife's totem, his totem was his wedding ring. Since he touched and knew the totem it made it useless, as he said to Ellen Page that no one should know the dimensions, weight and such. He was only wearing the ring during the time he was in the dreams, but outside of the dreams he doesn't have it on, thats because in his dreams they are together still. At the end of the movie he doesn't have his wedding ring on, and therefore the top will fall, and he made it back safely.