15. The Yo-Yo Is The Same One The Fourth Doctor Used (Kill The Moon)

Series 8 of Doctor Who has just finished and while Missy's identity and the truth behind the Nethersphere has been revealed, there's still a lot to uncover across these twelve episodes. Back when it was first resurrected in 2005, Who tried to keep references to the past to a minimum, serving as a hard reboot with much of the previous elements written out of continuity. As things have gone on, with a renewed interest in the classic run, recent series have hid more and more references for serious Whovians. Even a passing fan will understand the significance of the Doctor wearing a long scarf after his regeneration, or the copious nods to bow-ties. Today we're going to go a bit deeper, bringing you fifteen obscure easter eggs from the recent series you probably didn't pick up on.In Kill The Moon, to prove the gravity on the moon is stronger than it should be (watch out for time dilation), the Doctor uses a yo-yo, which only goes as far as the first yo. Eccentric and childish, it's classic Who. Literally, because that yo-yo is the same as used by the Fourth Doctor in a very similar case in The Ark In Space. The serial, which sees Tom Baker's Doctor land on an old space station and come up against an insect-like alien, deals explicitly with the future of humanity amongst the stars, something Series 8 looked at heavily. Apparently, Peter Capaldi insisted that the yo-yo looked as similar to the one Baker used almost forty years ago. So while it was probably intended as a little wink by writer Peter Harness, the Doctor himself made it implied it was actually the same toy.