On mine there was a 30-some minute documentary (in SD quality) that was on there plus some interviews with a few cast members. I didn't watch either -- but I think they're on one of the older releases (not sure if they're on the new 4K release or not)
Weirdly... I had "iTunes Extra" on this with a bunch of featurettes/etc from the 3D BR previously.
Now I just have deleted scenes.
But it's in 4K now...