Osgood continues to be a walking Doctor costume homage. After wearing a big, floppy scarf like the Fourth Doctor, her latest outfit has a leather jacket, Converse sneakers and a burgundy bow tie - favored by the War/Ninth, Tenth and Eleventh Doctors, respectively.
First time The Doctor's daughter and granddaughter are mentioned in an episode together.
Clara mentions the Doctor had four marriages. In The Doctor's chronological order: Susan's grandmother, Queen Elizabeth, Marilyn Monroe, and River Song.
Missy descends from the clouds with her umbrella opened. That and her costume mimics the titular character Mary Poppins (1964).
This is the first episode to show a scene mid-end credits.