Steven Moffat commented: "It's the 50th year of Doctor Who and look what's going on! We're up in the sky and under the sea! We're running round the rings of an alien world and then a haunted house. There's new Cybermen, new Ice Warriors and a never before attempted journey to the centre of the TARDIS. And in the finale, the Doctor's greatest secret will at last be revealed! If this wasn't already our most exciting year it would be anyway!"