So first off, I have to admit that this is one of those rumors that I wish would be true. According to NukeTheFridge, one of their sources informed them that the Blu-ray release of The Dark Knight Rises is going to include 30-minutes worth of extra footage! That’s already a third of an average full length movie.
Details of the rumor indicate scenes from Bane’s origins like how he learns to fight and more flashback scenes involving Liam Neeson as Ra’s al Ghul. It's easy to connect the former with the statement made by costume designer Lindy Hemming in an early interview with GQ:
“The other thing that you should have seen during that sequence is him being injured in his youth. So one of the fundamental things about his costume is that he has this scar from the back injury. Even if he hasn't got the bulletproof vest on, he still has to wear the waist belt and the braces. In that scene in the prison, where he's learning to fight the same way Batman learned to fight, he's wearing an early version of his waist belt. It's showing support, but it's not the finished one he eventually wears. He's also wearing an early version of his gas mask, all glued together...
If you look at the film, unless they've cut it -- and I'm sure they haven't -- there's a whole early section for Tom Hardy where he's fighting and being taunted by people. He's got chains on him, and he's standing on a wooden thing while people are attacking him. And in that scene, he's wearing a much more ragged, primitive version of the mask.”
But before you get all excited for this Blu-ray release, it should be also worth noting that Christopher Nolan isn’t known to indulge in the practice of director’s cut, especially of this magnitude. He didn’t do it for The Dark Knight and he surely didn’t do it for Inception either. But then again, one media writer did make a point about Nolan’s use of the IMAX format, which has a 165-minute runtime limit that might have hindered Nolan to push the entire movie’s length even further.
In other words, this is all still just a rumor after all.