Doctor Who: 14 Cool Details In Steven Moffat & David Tennant's Silence In The Library Commentary
2. Moffat's Son Was Behind The Camera For This Shot
Just before the episode draws to a close, there's a terrific little shot where the camera pans across a series of bookshelves, before coming to a halt when our protagonists enter the frame.
According to Moffat, his son helped out with this shot - he actually got to move the camera, and he also got to use the clapperboard.
Moffat doesn't state whether his son's take actually made it into the episode, but either way, getting to truthfully say "I filmed Doctor Who" is incredibly cool.