* ActingForTwo: Monica Dolan as Mave and Meg Carter in series 2, episode 3.
* EditedForSyndication: PBS, as is its wont, cut scenes for the American release. Fans, as is ''their'' wont, were enraged.
* HeyItsThatGuy!
** Sister Evangelina is [[{{Matilda}} The Trunchbull]].
** Sister Monica Joan is the Queen from ''Film/EverAfter''.
** Sister Julienne is Jessica 6 from ''Film/LogansRun'', Roberta "Bobbie" Waterbury from ''Literature/TheRailwayChildren'', and Alex Price from ''Film/AnAmericanWerewolfInLondon'', among ''many'' others.
** Chummy is Miranda from -- well, from ''Series/{{Miranda}}''.
** Nora Harding is Barbara Havers from ''TheInspectorLynleyMysteries'', using [[FakeBrit a dialect]] she hasn't used since 2007.
** Hey, isn't that nurse treating [[spoiler:Timmy Turner]] for polio in the second Christmas Special [[Series/CallMyBluff Sandi]] [[Series/{{QI}} Toksvig]]?
* HeyItsThatVoice: The narrator is Vanessa Redgrave, no less.
* IWantYouToMeetAnOldFriendOfMine:
** Creator/SharonSmall (Nora Harding, episode 2x05) previously played DS Barbara Havers on ''TheInspectorLynleyMysteries''. Jenny Agutter (Sister Julienne) made a guest appearance in episode 3x03 of that programme, ''A Cry for Justice'', playing Jemma Sanderson.
* RealLifeRelative: Screenwriter/show creator Heidi Thomas is married to Stephen [=McGann=], who plays Dr Turner. ([=McGann=] good-naturedly grumped that just because he's married to the head honcho doesn't mean he gets a preview of what's coming; he had to wait to find out whether Sister Bernadette and his character were going to end up together until he got his script. For the record, [[spoiler:[[TheyDo they did]]]].)
* RealLifeWritesThePlot: Episode 3x01 dealt with cystic fibrosis because Jenny Agutter lost two infant siblings to the disease, and her niece has it as well; she has since focused most of her charity work on finding a cure.
* ShipperOnDeck: Stephen [=McGann=] and Laura Main ship their characters almost as desperately as the fans do. Possibly more.
* StarMakingRole: For Jessica Raine, Helen George, Bryony Hannah, and Laura Main.