|Written by||Steven Moffat|
|Directed by||Rachel Talalay|
|Produced by||Peter Bennett|
“My name’s Doctor Who.”
Friendship drives the Doctor into the rashest decision of his life. Trapped on a giant spaceship, caught in the event horizon of a black hole, he witnesses the death of someone he is pledged to protect. Is there any way he can redeem his mistake? Are events already out of control? For once, time is the Time Lord’s enemy…
- World Enough and Time marks the first on-screen appearence of the original Mondasian Cybermen since the First Doctor television story, The Tenth Planet in 1966.
- This episode marks the return of John Simm’s Master, who last appeared in The End of Time in 2010.
This episode marks the first time that more than one incarnation of the Master has appeared on-screen.
- The Master’s line comparing the scenario to being more like a "Genesis of the Cybermen" is a reference to the 1975 Doctor Who story Genesis of the Daleks, which showed the Fourth Doctor being sent to the creation of the Daleks. Following the success of Genesis of the Daleks, a story entitled Genesis of the Cybermen was planned, but never produced.
- For the first time in the show’s history, the Doctor actually self-identifies using the name "Doctor Who".
- The Doctor notes Missy’s use of the TARDIS to retrieve him along with Bill and Nardole from Mars. (Empress of Mars)
- Blue-skinned humanoids are seen again. (The End of the World, The Pandorica Opens, Oxygen)
- The Master adopted the guise of "Razor" so Bill would not recognize him from his time as Prime Minister of the United Kingdom. (The Sound of Drums / The Last of the Time Lords)
- The Master is sporting a beard, similar in style to his previous incarnations. (Terror of the Autons–Frontier in Space, The Keeper of Traken-Survival) He also shows a love of disguises like his past selves. (Time-Flight)
- Missy not remembering being on the ship in her previous incarnation is similar to how the Eleventh Doctor didn’t remember meeting his other selves until "time caught up". (The Day of the Doctor)
- The original Mondasian Cybermen appear again and Mondas is shown on a screen, revealing it to be a twin to Earth. (The Tenth Planet)
- The Doctor has been on another space colony that orbited a black hole. (The Impossible Planet / The Satan Pit)
- The Doctor has to travel to a different time zone of the same location to rescue his companion, but arrives too late. (The Girl Who Waited)
- Bill‘s conversion into a Cyberman resembles the alternate Jackie Tyler (Rise of the Cybermen) and Yvonne’s conversion. (Doomsday) It also resembles Oswin Oswald’s conversion into a Dalek. (Asylum of the Daleks)
- The Cybermen are shown to be able to cry and feel pain. (Doomsday, Rise of the Cybermen)
- The Master has allied with Cybermen before. (The Five Doctors, Dark Water / Death in Heaven, Birth of a Renegade)
- The Doctor and Missy each mention how they met at the Academy on Gallifrey and how they chose their names that day, among other promises. (The Sound of Drums, The End of Time)
- The Doctor knocks out Jorj using Venusian aikido. The fighting style was prominently used by his third incarnation. (Inferno, Colony in Space, The Mutants, The Green Death, The Time Warrior, COMIC: The Celluloid Midas)
- The Doctor mentions the Master’s desire to destroy the universe rather than explore as they initially promised. (Last of the Time Lords, The End of Time)
- The surgeon explains that the headpiece of the cyber-suit acts as an emotional inhibitor so Bill won’t care for the pain. (The Age of Steel)
- In his fifth incarnation, the Doctor saw the Mondasians who remained on Mondas convert themselves into Cybermen for similar reason. (Spare Parts)
- Missy previously encountered the "Harold Saxon" Master. (The Abominable Showmen / The Five Masters)
- This is the fourth time the Doctor has witnessed the "genesis" of some form of Cybermen (Rise of the Cybermen/The Age of Steel, COMIC: The World Shapers, Spare Parts).
- The Doctor says going on an adventure is something he and Bill do on Saturdays, just as Wednesday used to be his day for adventures with Clara Oswald (The Bells of Saint John)
- The topic of the Doctor’s real name is discussed. (The Name of the Doctor) The Doctor again states how he actually likes being called "Doctor Who" (The Bells of Saint John). Missy also claims to know the Doctor’s real name; previously, River Song possessed this knowledge (Forest of the Dead) and Clara Oswald briefly did so before a time reset (Journey to the Centre of the TARDIS).
- Bill and Nardole, watched over by the Doctor, became Missy’s companions on a test trip to determine whether she could reform from her evil ways. While surveying the colony ship they were on,
- Bill was mockingly called the "exposition" and "expendable" by Missy. Bill was mortally wounded by a paranoid technician who was the only one left of his crew, due to her being human. Unable to save her, the Doctor allowed her to be taken by medical figures who had come from the lower levels of the ship as he understood were capable of healing her. He left a message in her subconscious for the moment she awoke: "wait for me".