* AbilityOverAppearance: Creator/LizzyCaplan almost didn't get the job, as the producers thought she was too pretty to play [[CoolLoser Janis]]. As such they gave her a more goth/alternative look rather than trying to dress her down.
* ActorSharedBackground: Betsy Heron gets offered tenure at Northwestern. Her actress Ana Gasteyer's alma mater is Northwestern.
* BillingDisplacement: When a Mean Girls game came out for the Nintendo DS in 2010, Creator/LindsayLohan, the film's star, wasn't on the cover. The tabloids had a field day with this. Ana Gasteyer who plays the minor role of Cady's mother is also credited before Creator/LaceyChabert and Creator/AmandaSeyfried, two of the protagonists.
* CaliforniaDoubling: As Creator/RogerEbert [[http://rogerebert.suntimes.com/apps/pbcs.dll/article?AID=/20040430/REVIEWS/404300306 put it]], "She enrolls in Evanston Township High School -- which, like all American high schools in the movies, is physically located in UsefulNotes/{{Toronto}}"
* ContractualPurity: The film's R-rated content was toned down when Creator/LindsayLohan was cast, as she was considered too family-friendly for such a raunchy film at the time. Likewise Lohan opted to play Cady rather than Regina, worrying about hurting her 'good girl' image.
* DawsonCasting: Regina George is played by Creator/RachelMcAdams, who was 24-25 at the time of filming. Also, Creator/LaceyChabert and Creator/LizzyCaplan were both 21 when the film was made. Creator/LindsayLohan and Creator/AmandaSeyfried, however, were both teenagers at the time.
** In the sequel, two of The Plastics - Mandi and Chastity - were played by actresses who were 22 at the time. Was subverted with Jo, Hope and Abby, played by actresses who were around the characters ages during filming.
* DeletedScene:
** Cady tries to give Regina a WardrobeWound by having a friend rig her cafeteria table so that it tips and spills food into her lap when she sits down. However, Karen sits where Regina was supposed to, thus becoming the prank's victim.
** Cady rigs the weighing scales to fool Regina into think she's lost weight.
** An extended version of Cady at Aaron's house where it's revealed it's only him and his mother.
** An ImagineSpot during the assembly where Cady imagines that Ms. Norbury says "your parents have been eaten by cannibals!"
** A longer version of the scene with well-wishers at Regina's bed. Her mother tells the congregation that Regina lost so much weight from being immobile that the doctors recommended Kalteen Bars. Regina gives a BigNo and the army of people rush outside just as Cady comes to the door. She throws the bouquet of flowers inside as she's swept away by the crowd.
** Just before going into the Spring Fling, Cady bumps into Regina in the bathroom. Regina says she's over the whole thing.
* FakeAmerican:
** Creator/RachelMcAdams, who plays Regina, is Canadian.
** In the sequel, Chastity is played by Australian actress Creator/ClaireHolt.
* ImageSource:
** GirlPosse
** MakeWayForThePrincess
* RealLife/MeanCharacterNiceActor: Creator/RachelMcAdams is the polar opposite of Regina; the crew made a point to cast the politest actress as the meanest character.
* PlayingAgainstType:
** Neil Flynn, who was at this time well known as the [[{{Jerkass}} sarcastic smartass]] Janitor on ''Series/{{Scrubs}}'' plays Cady's loving, caring, affectionate and utterly clueless father.
** Retroactively for Creator/AmandaSeyfried, who eventually became known for playing wholesome GirlNextDoor types. Playing a BrainlessBeauty who makes out with her first cousin is a tad different. She was nearly cast as Cady, which would have been within her eventual type.
** Director example: Mark Waters usually has supernatural elements in his films. There are none in this.
** Claire Holt was best known on Australian TV as the bossy, responsible Emma on ''Series/H2OJustAddWater'' - making a ReallyGetsAround character like Chastity quite different.
* ProductionPosse: The movie was produced by ''Series/SaturdayNightLive'' co-creator and producer Lorne Michaels, and written by Creator/TinaFey, who plays a supporting part, and also includes her SNL castmates Ana Gasteyer and Tim Meadows. She's also best friends with Creator/AmyPoehler.
* StarMakingRole: At the time of its initial release, it was considered to be this for Creator/LindsayLohan. In the longer run however, Creator/TinaFey was the one whose career really took off as a result of this film, with Creator/RachelMcAdams and Creator/AmandaSeyfried also benefiting quite a bit.
* UnintentionalPeriodPiece:
** It's telling that, in a DeconstructiveParody of high school cattiness and how even nice people get caught up in it, cyberbullying is never mentioned once, despite it becoming a hot topic by the end of the decade. Gretchen's cell phone (which only shows up in [[https://www.youtube.com/watch?v=_K4L9K8oUZ8 one scene]]) is a then-cutting-edge flip phone that's used to demonstrate how rich she is, the characters interact with and spread rumors about each other almost entirely through "low-tech" means (such as the "Burn Book", which is a physical, pen-and-paper journal as opposed to a private webpage or online group), and a [[https://www.youtube.com/watch?v=eLjMbaMazbs "three-way calling attack"]] could only work in a time when landline phones were commonplace. In the early-mid '00s, even teenagers were just starting to get used to the internet and cell phones being omnipresent forces in their lives as opposed to novelties -- Website/{{Myspace}} had been launched just nine months before the film was released, and had yet to really take off -- and this film's portrayal of technology marks it as a clear product of that immediate pre-WebTwoPointOh time.
** The showcasing of [[AlphaBitch Regina George]] and her family's [[https://www.youtube.com/watch?v=yEQV2OJVBx4 materialistic life]], while meant to show [[StepfordSmiler how empty and hollow her life truly was]] even in 2004, also marks the film as having been made before the Great Recession, when flaunting immense wealth was in style. While the scene of Regina's little sister shaking her booty to trashy pop-RAndB still resonates in the age of Music/MileyCyrus and twerking (and the fact that said sister is named [[http://en.wikipedia.org/wiki/Kylie_Jenner Kylie]] is HilariousInHindsight), the fact that she's shaking it to [[https://www.youtube.com/watch?v=pGL2rytTraA "Milkshake" by Kelis]] definitely doesn't (''Forever Young Adult'' even [[http://foreveryoungadult.com/2014/11/13/a-highly-scientific-analysis-of-mean-girls/ called the film]] a "2004 musical time capsule" in their retrospective). Regina's mom is also shown wearing 'youthful' clothes [[WereStillRelevantDammit in an attempt to be hip]]... which, in 2004, meant garish Juicy Couture sweatpants and tracksuits that, [[TropesAreNotBad in hindsight]], make her look [[AmazinglyEmbarrassingParents even more pathetic]].
** The portrayal of the AmbiguouslyGay {{Cool Loser}}s Janis and Damian illustrates how attitudes towards LGBT people among teenagers were evolving in the early-mid '00s. Regina suspecting that Janis is a lesbian was enough to get her to kick Janis out of her social circle and spread rumors about her sexuality, leading to her present outcast status, while the Plastics list Janis in the Burn Book as a "dyke" and Damian as "too gay to function". This sort of casual homophobia on their part was shown as a sign of their AlphaBitch tendencies even in 2004, but characters with such tendencies in 2014 would be portrayed as downright bigoted rather than merely callous, given that nowadays, homophobia is seen by teenagers as roughly on a par with racism. It illustrates how, while tolerance of LGBT people was growing, full equality and acceptance was still a ways away (this was the year when Massachusetts became the first US state to legalize same-sex marriage, an occasion that sparked controversy and [[YouCanPanicNow moral panic]]), and being gay, or even MistakenForGay, could make somebody an outcast.
* WhatCouldHaveBeen:
** In the original script, Gretchen was envisaged as plain-to-ugly (with a "sniveling whiny face") and part of the in-crowd solely for her wealth. Obviously, this was dropped when the very pretty Creator/LaceyChabert was cast in the role, but traces of the original perception of the character can still be seen in the film in Regina's obvious surprise that Gretchen was nominated for Spring Fling Queen.
** The film was a lot filthier before it was PG-13ified. See {{Bowdleri|se}}zation on the main page.
** Creator/AmandaSeyfried was nearly cast as Cady before producers felt she was better for Karen. Creator/LindsayLohan nearly played Regina but opted to play Cady instead, worrying that playing a mean girl would hurt her wholesome image at the time.
** Creator/ScarlettJohansson and Creator/AshleyTisdale auditioned for Karen, while Creator/JamesFranco auditioned for Aaron.
** Creator/TinaFey was approached about sequels for years and refused to do them. When the actual sequel came out - and was met with {{Sequelitis}} reactions - she said she regretted not writing one.
* WordOfDante: [[http://bust.com/mean-girls-10th-anniversary-reunion-cast-spills-secrets.html In an article for "Entertainment Weekly"]], the actresses were asked about what they imagined their characters as.
-->'''Karen:''' Manage or own a store that sells really cool dog attire, like Swarovski dog collars and Halloween costumes for animals.
-->'''Cady:''' In Africa with [[Series/TheOprahWinfreyShow Oprah]] working at children’s schools with family, teaching girls to be nice.
-->'''Gretchen:''' Running the Toaster Strudel Empire. She has curly hair and worked everything out with Jason.
-->'''Regina:''' She’s a [[TheRealHousewives Real Housewife]] and has found all her other Reginas.
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