This episode saw a rare use of the mild expletive "bitch" on the series, spoken by Missy. This is notable as the episode premiered pre-watershed hours on BBC One and Doctor Who is often considered a family-friendly television series. To further denote the rarity of this language on the show, the expletive was last heard in The End of the World (2005) by Rose Tyler, over ten years prior.
This episode is not the first time the Daleks are shown to have a concept of mercy. Previously in The Big Bang (2010), a Dalek says its records indicate that River Song will show mercy because she is a companion of the Doctor (and is subsequently proven wrong).
Davros says the Doctor is privileged to be able to use the only other chair on Skaro. This references The Survivors (1963) (the second episode of "The Daleks", the first Dalek adventure), when Barbara comments that on the Daleks' world, "there wasn't any furniture, now I come to think about it..." It was also brought up in Comic Relief: Doctor Who - The Curse of Fatal Death (1999), where the Doctor and his companion were tied to chairs by Daleks; when his companion asked why the Daleks had chairs, the Doctor promised to "explain later".
The Doctor thinks he will be shorter in his next incarnation; which is proven right. The Thirteenth Doctor noted "these legs used to be longer" when she jumped from one crane to another in The Woman Who Fell to Earth (2018).
Missy is seen in a sewer. Previously, in the spoof Comic Relief: Doctor Who - The Curse of Fatal Death (1999) also written by Steven Moffat, an incompetent version of the Master was shown falling into an absurdly vast sewer three times and taking three hundred and twelve years to climb out each time.