The safe of AD1 includes files on or pictures of various famous women: Sylvia Plath (marked terminated), Indira Gandhi, Jacqueline Kennedy Onassis (as Jackie Onassis, terminated), Rosa Parks, Janis Joplin, Mother Teresa (terminated), Princess Margaret (terminated), Katharine Hepburn, Margaret Thatcher (neutralized) and Marilyn Monroe (terminated).
During scenes in the school by the stairs there is a white marble bust of a female head. It is a copy of Miss Fritton as played by Alastair Sim in the original black & white St. Trinians films.
Kelly says she is working for MI7, which is the now defunct British Military Intelligence Section 7, and was part of the War Office set up to work in the fields of propaganda and censorship.
The treasure seen in the trailer consists of "gold" coins. These are actually Bulgarian currency coins of 1 and 2 stotinki (cents) made of brass-plated steel, not gold.
Toby Jones, the Bursar was also in Doctor Who, he played the Dream Lord in Amy's Choice.
so 4 cast of this movie and 3 of the prior who were, or are in Doctor Who.
David Tennant, Jodie Whittaker 2018's New Doctor, Talulah Riley (Miss Evangelista) in forest of the dead / silence in the library.