Jason Reitman read the script and wanted to direct it. He called up the producers on the phone with the intention of getting the job. The producers answered: "We are in editing right now, but I hope you'll like the film when it comes out."
When Barbara has had her meeting with the headmaster at which he reveals what he knows about her stalking of Jennifer Dodd, she throws up in a school toilet. In the background, on the wall, is written the graffiti: "Babs Covett = nasty old lezza. I want to lick her mangy twat."
When Sheba confronts Barbara about her diary, the makeup (eyeliner) she has smudged by crying changes. One moment she had dark thick eyeliner on, the next moment she has very little of eyeliner still on, and then the eyeliner comes back as before.
Steven is stated as being fifteen years old and in Year 10. Pupils become fifteen during Year 10 (except in exceptional circumstances). Later in the film, Sheba states that he is going to be sixteen in May, i.e. he was already fifteen before entering Year 10.