Whether you like it or not, we’re now halfway through this series of Doctor Who, and it’s time for the stakes to get higher; we now know who’s in the vault (or at least, who the Doctor thinks is in the vault), there’s a massive alien invasion waiting to strike, and oh yeah, the Doctor’s still blind. While you bite your nails waiting for next week’s instalment, here are our viewing notes with all the vaguely interesting things we noticed about this week’s episode. As ever, if you’ve noticed things we haven’t, leave them in the comments below and win the respect of your peers. It’s time for the return of the Master, the Doctor’s oldest frenemy. First introduced in 1971’s Terror Of The Autons, the Master is a childhood friend of the Doctor’s who ‘delights in deviousness’ and has tried to take over the universe on several occasions. The Master’s current incarnation, Missy (short for ‘Mistress’), first appeared at the end of Peter Capaldi’s first story Deep Breath in 2014 and revealed her identity in Dark Water later that year. Michelle Gomez is the fourth actor to play the role on screen on a recurring basis, following Roger Delgado (1971-1973), Anthony Ainley (1981-1989) and John Simm (2007-2010). Missy’s execution isn’t the first time a Time Lord has been sentenced in this way – it isn’t even the first time the Master has been executed. The beginning of the 1996 TV Movie saw the Time Lord (played by Gordon Tipple, in a career-defining role) executed by Daleks, with his last wish being that the Doctor come and pick up his remains… The first Time Lord execution was in 1969’s The War Games, which saw the villainous War Chief snuffed out by the same judges who then sentenced the second Doctor to regeneration and exile on Earth. The following episode, The Witch’s Familiar, saw Missy stranded on Skaro with the Daleks, and this was the last time we saw her – something she alludes to here. We shouldn’t be too surprised that she escaped, as this is a particular talent of the Master’s. Previous end-of-story scrapes have included being trapped inside a collapsing city (1982’s Castrovalva), being burned alive (1984’s Planet Of Fire), being sucked into the Eye of Harmony (The 1996 TV Movie) and being sent back into the heart of the Time War with a vengeful Rassilon (2010’s The End Of Time). The Doctor’s retirement into domestic bliss on Darillium refers, of course, to the 24 years he spent with River Song during their final night together, which began in 2015’s The Husbands Of River Song. The two married in 2011’s The Wedding Of River Song. ‘In extremis’ is a Latin term meaning ‘in extreme circumstances’. Perhaps more appropriate here is the medical use of the term, ‘at the point of death’. Extremis was also the name of a technological virus in Marvel’s Iron Man comics, and the Extremis story arc formed the basis for 2013’s Iron Man 3. Though there is no evidence to suggest that Pope Benedict IX was a woman, he was certainly controversial; he is believed to have been the first primarily homosexual pope, and his time in office was filled with salacious rumours about his lifestyle, which led to his first expulsion in 1044. He returned to the role two more times before being driven away by german troops in 1048. The Pope does indeed have a ‘Popemobile’ – in fact, he has a number of them – though anyone expecting atomic batteries to power and turbines to speed will be disappointed; they are regular cars that have been customised to allow the Pope to sit or stand above ground level to be more easily seen by the people – in short, it’s the modern equivalent of the old practice of having twelve men carry him around on his throne. And, unfortunately, ‘Popemobile’ is just a common nickname for the vehicles – Pope Francis isn’t a fan of the name, feeling it sets him apart from the people. There’s something of Koji Suzuki’s 1991 novel Ringu about the idea of a text which makes all who read it kill themselves. That book (and its subsequent Japanese and American film adaptations) featured a cursed videotape (remember those?) that would cause the death of anyone who watched it within seven days, unless they made a copy and passed it on. Bill isn’t the first companion whose mother has fallen for a Howard; Howard Foster was the stepfather of fifth and sixth Doctor companion Peri in Planet Of Fire, while Rose Tyler’s mum Jackie was dating a fruit and veg seller called Howard at the time of 2005’s The Christmas Invasion. With Jackie having been presumed dead (but actually gone to live on a parallel Earth) the following year, could a heartbroken Howard have moved to Bristol away from all the alien invasions and started to move on with his life..? The Doctor has battled monks before; the eleventh Doctor took on the Headless Monks in 2011’s A Good Man Goes To War, while the twelfth faced King Hydroflax’s monk bodyguards in The Husbands Of River Song. In 2006’s Tooth And Claw, the tenth Doctor foiled a plot by ninja monk Father Angelo and his Brethren to turn Queen Victoria into a werewolf. And the second Doctor had a hard time proving to a group of Tibetan monks that he wasn’t working with the Yeti in 1967’s The Abominable Snowmen. Of course, there’s also the Meddling Monk, a mischievous Time Lord who plagued the first Doctor in 1965’s The Time Meddler and The Daleks’ Master Plan… The Doctor may not have sat down for a Catholic confession session, but that doesn’t mean he hasn’t confessed – he was trapped inside a Time Lord ‘confession dial’ in 2015’s Heaven Sent, and confessed several things whilst in there. And it did indeed take him a long, long time – because he didn’t give the one confession the Time Lords wanted from him, he was stuck inside the dial for over four and a half billion years. Throughout the 2014 series, the new twelfth Doctor wrestled with the question of whether or not he was a ‘good man’. This episode references the realisation he finally came to in that year’s finale Death In Heaven: “I’m not a good man. And I’m not a bad man […] I.. Am… An idiot! With a box, and a screwdriver. Passing through. Helping out. Learning.” ‘Harry Potter’ hasn’t always been a dirty word to the Doctor; in 2007’s The Shakespeare Code not only did the tenth Doctor admit to having cried at the ending of the then-unpublished seventh book, but Martha Jones helped save the day by giving Shakespeare the word ‘Expelliarmus’ – a disarming spell used in the Potter books. In 2008 Russell T Davies wanted to have the series’ writer JK Rowling guest star in that year’s Christmas special, but David Tennant (Who had previously appeared in Harry Potter And The Goblet Of Fire) was against the idea, insisting it would have been too much like a parody. Weeping Angels and Demons Both CERN and the Vatican (complete with mysteries underneath its surface) appeared in Dan Brown’s 2000 novel Angels And Demons (And also the Tom Hanks film of the same name). The Doctor landed the TARDIS in the Oval Office in 2011’s The Impossible Astronaut, where he encountered President Richard Nixon, who had been receiving mysterious phone calls from a small child. Nardole references Star Trek’s holodeck – first introduced for the pilot episode of Star Trek: The Next Generation in 1986, the holodeck was a programmable 3D holographic projection suite in which crewmembers could play out their (usually innocent, but not always) fantasies against realistic and tangible settings whilst on a long-haul flight in deep space. The holodeck was responsible for a number of stories where the characters didn’t realise they were in the middle of a simulation. It was also where the TARDIS landed in the Star Trek/Doctor Who comic book crossover from IDW. We’ll finish on a really nerdy one with scope for input from the rest of you, because we know you lot love a challenge… The priest who emails the files over to CERN has a full inbox. Names that we were able to make out (bear in mind we weren’t watching this in HD) included Bill Pullman (who appeared in Torchwood: Miracle Day); Phil Bond, the actor who sadly passed away in January; Christina Tom, credited as standby art director on this episode; Daryn McLaughlan, who isn’t credited on the programme but has worked as an art director on Broadchurch and Agatha Raisin among others; Peter Dukes, who may or may not be the actor with several uncredited roles on Who through the 70s and 80s; and Rob Hull, who holds the record for the largest collection of Daleks (and the most misspelled letters asking what Grotbags was like to work with). Those are our best guesses. Four more names we could make out that don’t seem to mean anything are Franco Esposito, Clarissa Heart, Albertina Ricci and Stefan Anchorage. But there were more on that page, so if you’re able to work out what they are and what their relevance might be, let us know in the comments below!