Colin Baker, who played the Sixth Doctor, visited the set when filming was in progress.
The inclusion of the Titanic in a story has been hinted at many times since Doctor Who came back in 2005, the most recent case is when a White Star line sticker was shown on the back of Larry's clipboard in the series three episode 'Blink'.
As the Doctor tries to guess the override protocol code for the Heavenly Host, he calls out various numbers (including "666"). One of the numbers is "42", a reference to "The Hitchiker's Guide to the Galaxy", written by Douglas Adams, a former "Dr Who" Script Editor, and creator of the computer game "Starship Titanic", which takes place on a space-going "Titanic".