Roots: Modern new age cults (the use of crystals, 'balance' as a buzz-word, suspicion of modern medicine). The Eight Truths' 'interview' stage (involving personal questions and a measuring device) is reminiscent of a certain high-profile, litigation-baiting celebrity 'religion'. The Beagle 2 Mars probe (the reception to the fate of the Terra Nova probe). 'Mary''s hypnotic commands include a line from The Beatles' 'Tomorrow Never Knows' ("close your mind, relax and float downstream") Kelly refers to the Kennedy assassination.
Technobabble: Pulonium 210 is very radioactive (as it is unstable, all isotopes of polonium are)
Double Entendres: "I'm going to book a taxi and check myself out."
"Hold it in front of you so I can touch it. That way we can communicate better."
"Don't worry, I won't let any spoilers out"
Continuity: Environmental catastrophes continue (see: Links) with week-long storms battering the Caribbean and blamed on climate change.
The Eight Truths' self-named Centre of Balance is in the former BBC Centre, whilst its base of operations is in the abandoned  Olympic village. The 'programme' was founded in 1987 by Clarke Goodman using cribbed philosophy from other religions (the Buddhists have issues with him) and some Metebelis crystals he discovered while potholing with friends in Yorkshire. By the end of this episode the group has 244 million members worldwide, having increased fivefold in as many years
Britain's space programme is in full swing, although it retains a reputation for amateurism. Its Terra Nova probe, four years and seventy-five million pounds in the making goes missing four days from its expected engagement with the exosphere of Mercury, ostensibly on a mission to follow the earlier Messenger probe and collect water samples. Its onboard computer system comprises two command and data, and two guidance and control, each powered by a Mongoose 5 processor. NASA's Solar probe lost contact two days previously. There is a tracking station in Buckinghamshire.
The stellar manipulator can manipulate all forms of energy from all forms of sun.
The Headhunter is not human, and says where she came from her people evolved differently; there are more people with psychic abilities and it is more commonplace.
The Doctor says the TARDIS enjoys talking to other computers.
The Doctor relies on his UNIT credentials to gain access to the Buckinghamshire station - indeed, UNIT does vouch for him. One hour's sleep is more than enough for him. He likes his tea white, no sugar. Shutting down his respiratory system is enough to induce a coma, which he lies in for twenty-three days.
Future History: It is implied that even in 2015 relations between the United States and Cuba remain prickly.
Location: London and Buckinghamshire, October 21st through to the 10th of November 2015
The Bottom Line: Cheeky. Robson's I-Can't-believe-it's-not-Scientology cul- sorry, self-improvement programme is a hoot, and Stephen Moore and Sanjeev Bhaskar's casting provides some welcome variety in voice. Once the villains crawl into the story the surprises have disappeared before you can say "strange blue crystal", but it's all done with such breezy aplomb you can't complain.