In the Summer of 2017, the BBC began an effort to complete the serial officially, using newly recorded dialogue from the original cast, newly filmed live action material, newly recorded incidental music and sound effects and new animated footage, to complete the missing segments. The new material was produced by the same team that undertook the 2016 animated edition of the 1966 serial The Power of the Daleks.
(Around 19 minutes) one of the books in Chris's room is called 'Zaphod: My Stories.' This is a nod to the character of Zaphod Beeblebrox from the 'Hitchhikers Guide To The Galaxy' books, written by Douglas Adams, who also wrote Shada.
Throughout most of the story, the Doctor (or far more likely Tom Baker) refers to the character Chris Parsons as 'Bristol'. Daniel Hill who played Parsons was born in Bristol.
Another book in Chris' room is "Hyperspace Bypass Planning Laws". This is yet another reference to Hitchhikers's Guide to the Galaxy.
K-9's dog collar (visible in a closeup when he first appears) is a similar pattern to the Doctor's scarf.