Eight years later, we now have a definitive answer thanks to Michael Caine, who revealed a little behind-the-scenes while attending a recent screening of the film in London.
“When I got the script of Inception, I was a bit puzzled by it,” Caine said. “And I said to [Nolan], ‘I don’t understand where the dream is.’ I said, ‘When is it the dream and when is it a reality?’ He said, ‘Well when you’re in the scene, it’s reality.’ So get that — if I’m in it, it’s reality. If I’m not in it, it’s a dream.”
There you go, Inception fans. Since Caine is in the final scene, it’s reality. Case closed. The totem falls.
Watch Inception again and again with this new information.