Doctor Who: 13 Cool Details Russell T Davies Just Revealed About The Stolen Earth & Journey's End
2. Donna Briefly Mentions Rickston, A Character From Voyage Of The Damned
When DoctorDonna finally buckles under the immense strain that the Time Lord DNA is putting on her weaker human brain, she starts babbling random sequences of words and names.
Listen closely, and you'll hear her mention "Rickston", a character who appeared in 2007 Christmas special Voyage of the Damned.
During the Journey's End watch-along, Davies tweeted that he chose this name specifically, in order to illustrate that DoctorDonna's mind is full of negative thoughts (in Voyage of the Damned, Rickston is painted as a selfish and cruel man).
While Donna wasn't actually in Voyage of the Damned, the Doctor was, and it's the Time Lord part of her brain that allows her to recall Rickston.