We're pretty excited about Looper, which is shaping up to be the next big mind-job flick. So when we nabbed Looper director Rian Johnson and actor Joseph Gordon-Levitt at WonderCon, we had to pump the duo for all the time-traveling mob murders plot info possible.

Watch Rian Johnson explain his time-travel picture with wild gestures, and learn what movies Gordon-Levitt watched to play a younger version of Bruce Willis, a.k.a. his future self.

I know that [your previous film] Brick was inspired by the Dashill Hammett mystery novels — was Looper inspired by any works at all?

Rian Johnson: Not specifically the way Brick was. No, Looper, it's a time travel movie so we obviously go back to a bunch of other time travel movies to kind of see how they did it. Looper was really kind of inspired by notion of, if you were sitting across from yourself 30 years from now — your older self — what would that conversation be like? Joe plays the main character, Bruce Willis plays the older version of the main character, and they kind of sit across from and have it out at one point.

How do you delineate the difference between 30 years in the future versus 60 years in the future?

Rian Johnson: That's always the first step. We had a really talented design team on this movie. So working with them and thinking about the world, "So this is 30 years?" because you see both of those things in the move. And that's just the kind of scifi world building that you get your head inside — it's kind of the fun part.

I know with the time machine in Primer if you go in for 30 minutes, you get 30 minutes. Can you explain to me how the time machine in Looper works?

Rian Johnson: No way. I'm not as smart as Shane Carruth by a mile. I can do this [makes wild hand gestures] and that's kind of how it works!

Since you play the younger version of Bruce Willis, did you return to any of his old work to look for inspiration, such as Moonlighting?

Joseph Gordon-Levitt: Yeah well, a lot of it, yeah. But I wasn't necessarily looking at his older stuff — I was looking at his most recent stuff. Because I wanted to sound like him now, I didn't want to sound like him then. I wanted there to be a match. I wanted the audience to think, "Oh yeah, that's the same person." So I was listening to Sin City a lot. And Red. And then the classics of course, the Die Hard movies, things like that.

Looper will hit theaters on September 28.