The Doctor asks young Kazran if he's ever seen Mary Poppins, to which Kazran answers no. The Doctor replies "Good, 'cause that comparison would've been rubbish."
The crashing cruise liner starship in this episode is a "Galaxy Class" starship, same as the Enterprise-D. Its bridge is also laid out similarly, and at the helm is a character wearing vision-augmenting eyewear.
Michael Gambon stars in both
Reference to the upcoming Christmas special
River accusses the Doctor of being married to Marilyn Monroe and in "A Christmas Carol" the Eleventh Doctor says he has just got accidentally engaged to her.