Camilla Fritton's dog, Mr Darcy, is named after a Jane Austen character from "Pride and Prejudice" (1995), as played by Colin Firth in the 1990's adaptation
The picture in Miss Fritton's study is a painting of Alastair Sim, as he played the original role in the original films. The bust that is destroyed by Annabelle's hockey blow also has the features of Sim.
When Colin Firth first makes his inspection of St Trinian's, and is tossed out of the Posh Totty's window, he walks to the hockey field wet, in a white shirt with his jacket over his arm. This is reminiscent of the part he played in the 1990's mini series "Pride and Prejudice" (1995), where he does a scene in the exact same way as depicted here.
The painting the girls are stealing is called "Girl with a Pearl Earring", which is also the title of a movie (2003) in which Colin Firth played the painter of that picture.
When Geoffrey and Camilla meet again, she says "Another time!" and he answers "Another country!", which is the title of the movie, in which Rupert Everett and Colin Firth first starred together.
There is many references to "Pride and Prejudice" (1995). For example: Fritton's dog is Mr D'Arcy, one of the girls mentions Colin Firth, Colin Firth dripping in water after falling into the unused fountain and Stephen Fry asking the question "Which book was originally titled "First Impressions" (A: Pride and Prejudice).
The character Camilla Fritton parodies Camilla, the Duchess of Cornwall in both mannerisms and dress.
The animated sequence during the heist plan are a stylistic nod to the original St. Trinian's cartoons drawn by Ronald Searle that inspired the movies.
The uniforms that Posh Totty (when they are at the Schools Challenge competition) wear are based on the original St Trinians uniforms from the original movies. Except the school's emblem is smaller.
During a deleted scene, Thwaite is talking to his colleagues about trying to reform St Trinian's. One of his colleague's announces "Let those wildcats beware." As a heading for a newspaper article. This line is paying homage to the movie The Wildcats of St. Trinian's (1980).
When the Chavs make over Annabelle, her hairstyle is based on UK rapper Lady Sovereign's style.
When Kelly suggests they steal the 'Girl With a Pearl Earring' portrait, the Posh Totty group reply "Oh my god, you want us to steal Scarlett Johansson?", referring to the film Girl with a Pearl Earring (2003). Colin Firth, who plays Geoffrey Thwaites in this movie, played the painter in the film with Johansson.
The movie was inspired by the original drawings of the girls of St. Trinians by Ronald Searle.
George Cole who played Flash Harry in the original series of films was offered a very tiny cameo, which he rejected.
The concept and name for St Trinian's was originally taken by Ronald Searle from St Trinnean's school in Edinburgh, which was established by Miss C. Fraser Lee and opened on 4 October 1922 with sixty girls, at 10 Palmerston Road. The school has since closed down, and is now Edinburgh University's Pollock Halls (of Residence). The school's existence became widely known when it advertised a reunion coffee party for old girls in The Scotsman in September 1955. By this time the fictional school was very well-known; the typesetter incorrectly used Searle's spelling in the advertisement. In an interview with the "Sunday Express" the headmistress firmly denied that her girls were anything like their fictional counterparts.