SAN DIEGO (AP) — The big time-travel paradox of the sci-fi thriller “Looper” is whether Joseph Gordon-Levitt is playing a young Bruce Willis or whether Bruce Willis is playing an old Joseph Gordon-Levitt.

Gordon-Levitt, co-star Emily Blunt and writer-director Rian Johnson gave the Comic-Con fan convention Friday a sneak peek at footage from “Looper,” which centers on a hit man who’s supposed to kill his future self.

To play the young assassin, Gordon-Levitt, 31, spent three hours in makeup every day to have a prosthetic nose and other cosmetic tweaks applied to make him look more like the 57-year-old Willis.

Time travel allows the mob to get rid of people by sending them into the past, where a hit man awaits and victims can be disposed of with no questions asked.