Doctor Who: 10 Easter Eggs, In-Jokes And References In The Magician's Apprentice
4. Bors
While 'meditating' (actually doing anything but) in Medieval England, the Doctor seems to have got himself a new companion in the form of Bors. He also features in the prequel, The Doctor's Meditation.
While it doesn't have any special Doctor Who meaning, Bors is actually the name of one of the Knights of the Round Table in Arthurian legend. Interestingly, the Seventh Doctor story Battlefield set up the fact that sometime in his future the Doctor would become the legendary magician Merlin.
Is the appearance of Bors a hint at an Arthurian storyline to come either later this series or next year? Of all the Doctors, Peter Capaldi would fit the bill for Merlin best. The title of this episode even refers to him as a magician.
You know where you heard it first if this turns out to be true...