Peter Davison (Inspector Henry Christmas) and David Tennant (Max Valentine) are both well known for playing the Doctor in "Doctor Who". Davison played the Fifth Doctor in Doctor Who (1963) from March 1981 to March 1984 while Tennant played the Tenth Doctor in Doctor Who (2005) from June 2005 to January 2010. Tennant married Davison's daughter Georgia Tennant on 30 December 2011, making him his son-in-law.
In her speech to the school, Mrs. Bradley says that the previous year Amelia Earhart flew the Atlantic and that women finally got the vote. These both took place in 1928, allowing the events in this episode to be dated to 1929.