The mock newspaper just before the end has a line stating that Ringo is upset at St Trinians being honoured. This is a reference to many establishment figures voicing complaints at The Beatles being recently honoured with MBEs.
Schoolgirls from a Catholic convent school in Altona, Hampshire were used as extras in the film.
When the St. Trinian's school library is being moved into the new building, the French Mistress (played by Carole Ann Ford) accidentally drops four paperbacks from a pile of books, and the camera zooms in on their covers: The Perfumed Garden, by Cheikh Nefzaoui; Lady Chatterley's Lover, by D.H. Lawrence; The Carpetbaggers, by Harold Robbins; and Fanny Hill, by John Cleland. All four are erotic classics with scandalous reputations, regarded (at the time) as suitable only for men - hence the joke of their being seen in a girls' school. The last three had had recent movie adaptations in Lady Chatterley's Lover (1955), The Carpetbaggers (1964), and Russ Meyer's Fanny Hill (1964); and the D H Lawrence novel had recently been the subject of a sensational criminal trial in London, in 1963, in which the publisher had been prosecuted for obscenity.
George Cole (Flash Harry) and Michael Ripper (Eric the liftman) are the only actors to appear in all four of the original "St. Trinian's" films.
When Channel Four's Film Four channel showed the movie, in December 2015, the source appeared to be the same 4:3 side bar cropped full screen dirty print version that was also previously issued as a free DVD. Presumably either the wrong Archive version was sent, or the original elements haven't had a wide screen re-master, if they are still usable.