This episode stars four actors with connections to Doctor Who. Paul McGann played the Doctor in Doctor Who: The Movie (1996). Jason Watkins played Webley in Doctor Who (2005). Louise Jameson played companion Leila to the 4th Doctor in Doctor Who (1963) and Naoko Mori played Toshiko Sato in Doctor Who (2005) as well as in Doctor Who spin off Torchwood (2006).
Naoko Mori, who played Toshiko Sato in Torchwood (2006), says to Paul McGann, who played the Doctor in Doctor Who: The Movie (1996), "It's smaller on the inside" - an obvious reference to the Tardis (It's bigger on the inside).
Claire Skinner also has a Doctor Who connection. She guest starred in the Matt Smith 2011 episode "The Doctor, The Widow and The Wardrobe".
First episode in the series not to be written by Robert Murphy.