Bad Wolf Reference: Gwyneth looks into Rose's mind and sees "...the darkness...The Big Bad Wolf!"
Dickens cries, "What the Shakespeare?", a play on the common exclamation, "What the Dickens?" Contrary to popular belief, the phrase has nothing to do with Charles Dickens; "Dickens" is a euphemism for the Devil. Riffing on this comment, in the 2006 Big Finish Productions audio drama The Kingmaker, William Shakespeare cries, "What the Geoffrey Chaucer?" William Shakespeare used the phrase "What the Dickens" in his work (The Merry Wives of Windsor, Act III, scene ii).
Gabriel Sneed was initially conceived to be a younger character, with David Tennant in mind for the role.
Eve Myles, the actress playing Gwyneth, went on to play Gwen in the Doctor Who spin off series Torchwood (2006). The Doctor refers to this when he first meets Gwen in Journey's End (2008).