As Doctor Who fans, we all love the in-jokes and references that only a die-hard fan would understand, whether it's Tennant in a gas mask saying "Are you my mummy?" or as subtle as Smith remarking that he used to own a patchwork umbrella (referencing his sixth incarnation to be precise). References in a half-century old show are moments that fans can bond over; they're checkpoints for the anoraks, and it gives us Whovians an "I know something you don't moment" over the casual viewers in our families who put up with the show. Perhaps more exciting and intelligent however, are the outside references and allegories, and I'm not talking about the Nazi/Dalek similarity, I'm talking about the Whoniverse itself. These are moments when someone references something that relates to Doctor Who, not the Doctor, and not just a moment of continuity. Like LINDA for example, being a portrayal of us fans, or the Doctor receiving the phone call about the Brigadier's death and the sadness of that scene carried when you consider that Nicholas Courtney had died in real life. These aren't just nods to those of us that watch and rewatch every Who episode, they're golddust for the fans that trawl Wikipedia, YouTube and Steven Moffat's bins for extra nuggets of information, such as Matt Smith's love for Radiohead or the exact dimensions of a TARDIS. Let me take you through five more ingenious, amusing and downright cute moments of NewWho writers winking at us through our very screens.