For the superfans out there, writer/director Rian Johnson has created a free, downloadable director's commentary track for Looper that he recommends listening to on an iPod during a second theatrical viewing of the film.
He writes on his Tumblr, "I recorded a commentary track to be downloaded, put on an ipod and listened to in the theater as you're watching Looper. This is an odd thing I tried with Bloom, and have gotten a few requests for it again, so here it is. It is totally different from the commentary track that will be on the Blu/DVD, a bit more technical and detailed. Needless to say, this is NOT to be listened to on a first viewing, or before you've seen the film. Also, please work it so that a glowing screening is never out of your pocket during the movie."
Download it here.