Clara Oswald’s arc as the ‘Impossible Girl’ was eventually revealed to be that she has traveled through the Doctor’s personal time stream, and ‘saved’ the Time Lord in every one of his regenerations without him knowing. This explained why the Doctor had met two versions of Clara before, but the coincidences didn’t end there. Clara’s birthday is the 23rd of November, when the show officially first aired in 1963, and the date her mum died was the date that Rose Tyler was supposed to have met the Doctor in Rose. Coincidence, or absolutely totally on purpose? Most certainly, the latter.
3. “Are you my mummy?” (The Poison Sky)
Steven Moffat’s triumphant WWII two-parter The Empty Child/The Doctor Dances brought with it its own sinister catchphrase, when humans began transforming into gas mask creatures who could only say: “Are you my mummy?” Down the line, it seems the Doctor can’t resist harking back, with David Tennant quoting it whilst wearing a gas mask in the Poison Sky, and Peter Capaldi throwing in a reference to a very different kind of mummy in Mummy on the Orient Express.
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