That is, without the character limit: how they incorporated general relativity into the CGI. To make accurate images of the black holes and wormholes, they had to trace a light ray through curved spacetime for each pixel of the image, whereas ordinary CGI just traces along straight lines. As I mentioned somewhere above, this will be the first Hollywood movie ever to give us accurate images of these things.

And doing it required a major rewrite of the software and hugely more complex computations. Here's the story:

http://www.wired.com/2014/10/astrophysics-interstellar-black-hole/

Kip mentions at the end of the video that they're building two research papers out of this work. As far as the astrophysics research paper, I'm not sure what he's talking about, because these calculations have been done for decades now (just not at such high resolution using such pretty starfields). The thing about the accretion disk "tilting up" behind the hole is something that I think I already mentioned in this thread. But anyway, it's certainly an enormous advance in computer graphics methods, and it wouldn't entirely surprise me if they discovered some astrophysical effects along the way.