SAN DIEGO - 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.
But much of the transformation comes from Gordon-Levitt's mimicking skills. He says he watched Willis' movies over and over and listened to the actor's dialogue again and again on an iPod.
Much of what he aimed for, however, was capturing the cool essence of Willis, Gordon-Levitt said.
"I'm not a good mimic, to be honest. I don't do good impressions," said Gordon-Levitt, who also co-stars in next week's Batman finale "The Dark Knight Rises." "I didn't think an impersonation would be appropriate, anyway. It would just be distracting. So I just tried to internalize and do something that made sense to me. ...
"The most I learned from him is just hanging out with him," Gordon-Levitt said. "He's a sweetheart and he loved this job. He was clearly there to play."
The movie opens Sept. 28.
"Looper" is set late in the 21st century, when murder has become difficult to carry out. 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.
Johnson had previously directed Gordon-Levitt in the 2005 low-budget drama "Brick," when the filmmaker first raised the idea of the time-travel story. He wound up writing the script specifically with Gordon-Levitt in mind, even naming the character Joe.
"We've just been dying to work with each other again," Johnson said. "It's always best to make movies with your friends."