...much. But the directors commentary has RTD, Phil Collinson and Julie Gardner introduce themselves, then RTD adds "and we're naked!"
It also has another track, which is one of those things where someone is narrating what's going on for partially-sighted viewers. Which is cool, and means I can play it when I'm laying in bed, eyes closed, thinking of Captain Jack, big bottle of vaseline nearby... OK, I know, way TMI...