Diablo Cody: In the Melody Lane sequence. At first, you just see her holding a drink but later, when Jennifer says she'll score some alcohol by "playing Hello Titty with the bartender", the bartender who serves her turns out to be Cody.
The name 'Needy' Lesnicky comes from writer Diablo Cody's initial intention to have the character be of a 'needy' disposition. She later decided against this as she felt she had seen enough nerdy stereotypes in high school set movies.
In a February 2016 interview with the New York Times, while trying to illustrate how completely the studio's (all-male) marketing department misunderstood the point of this movie, director Karyn Kusama recalled that one of their marketing ideas was for Megan Fox to do live chats with amateur porn sites. Kusama said that she begged them to not even mention the idea to Fox because "she will become so dispirited....It was crushing."
The demon who possesses Jennifer Check (Megan Fox's character) closely resembles a succubus (plural succubi), from Jewish, Christian, and Sumerian mythology/theology. It is said that succubi seduce men, and fornicate with them until they are "drained" (in the movie, getting "drained" could mean getting drained of blood instead of semen). Some possible examples of succubi are Lilitu (from Sumerian mythology), Lilin, and Lilith (both from Jewish theology).
Jennifer's surname 'Check' was initially intended only to be a place holder name. It comes from writer Diablo Cody using the phrase 'check' to express the filling of the various required roles, e.g "Jennifer - check, Needy - check" and so on. The name was never changed and features in the final film.
The trivia items below may give away important plot points.
According to the original script, Needy was not supposed to be seen killing the band members of Low Shoulder. The script ended with Needy retrieving the Bowie knife and riding away with the driver who picked her up. This leads to the speculation that the writer originally intended to allow viewers make predictions for themselves to what happened afterwards.
this movie shares some similar plot points with the movie Ginger Snaps, (both movies involve two female characters that are closed at first, but become enemies, Both movies involve one of the characters being attacked t night in the woods but surviving and becoming evil, Both movies involve the evil character becoming rude to the good one, In both movies the character turned evil starts killing boys from school and eating them, in Both movies the good character finds a way to kill the evil one searching in the School's library, In both movies the love interest of the good character is bitten and killed by the evil character, and both movies end around a school party as well as ending with the good character stabbing the evil one in the heart in their own home. At the end of both movies the good character is bitten and becomes evil as well.)
In the scene where Jennifer seduces Needy (before they kiss), Jennifer is wearing an "Evil Dead" t-shirt. Plus there is an "Evil Dead" poster on the wall of the bedroom which is center screen for part of the scene. Both movies have an evil force in the woods, that take possession of a young female, and that preys on school friends.