As Martha Jones first walks in and sees Ianto there is a news clipping on the wall saying "New Mayor, new Cardiff" and it has a picture of Margaret Blaine, the Slitheen whom the Doctor met in Boom Town (2005).
Martha Jones says, "I am a camera." Jack says, "As Chris Isherwood once said to me as we were cruising the Kurfurstendamm." In the 1930s Isherwood wrote The Berlin Stories, based on his experiences in Berlin in the years just before the Nazis came to power. Those stories became the play "I Am A Camera", which then became the musical "Cabaret". Kurfurstendamm was The Street for the best shops, theatres, restaurants, and night clubs.
This episode takes place in 2008.