Didn't know of that one.
I can't think of 2 fairly blatant ones.
One of which should be known to all.
The Doctor says Arthur Dent is a nice guy in "The Christmas Invasion."
Back in, I think, "Destiny of the Daleks," the Doctor has a copy of one of Oolon Colluphid's books. (Colluphid wrote a series of books about the origins of the universe and how blindingly dumb God was.)