Patrick Schwarzenegger admitted that he found it difficult to be so mean to the rest of the cast. Director Amy Poehler helped push him when she thought he was being too nice.
The Linda Lindas (the band who play at the mahjong club) are a real band. Amy Poehler saw them as an opening act for the band Bikini Kill, and had them perform and record music for the movie.
Claudia talks about buying a tank top for a Mean Girls (2004) costume. Director, producer, co-star Amy Poehler played Mrs. George, Regina George's mother, in Mean Girls.
The song that the Rockport High School marching band plays at the assembly and at the football games is to the tune of "For Boston", the traditional fight song of Boston College and Boston College High School. Director and co-star Amy Poehler is a Boston College alumna, and graduated from the college in 1993.