The jump would be from limbo to the plane. Cobb also seemed to be referring to the start of the dream. Everything we saw within the dreams appeared to have people moving around like normal.
When doing the "Dream Orientation" with Adrianne he says to her "You never really remember the begining of the dream, do you? Let me ask you how did we get to this cafe?"
This seems to apply through the climax dreams where the characters when they start each new "level" they're simply dropped into a situation. In the car, on the street, suddenly in the hotel in their various positions (the one dude as a hot, blonde, twilight vampire), on the mountain top guns at the ready. With the ending scene Cobb's not dropped into the middle of anything, he's "dropped into" waking up on the plane. Where he'd expect to be if he woke up and he remembers every step along the way between there and walking into his home with his older