The idea of John Tucker wearing a thong was not in the original script. Originally, Kate talked him into shaving his head. Betty Thomas thought making him wear a thong was funnier. While shooting, the extras were actually taking pictures of him with their phones.
Since shooting took place during the actual school year in an existing high school, the crew had to ask students for permission to use and re-dress their lockers for shooting.
In the script, the school didn't have a specific mascot, but while filming on location at an actual high school, the film adopted their mascot, the Kodiaks.
Impressively, every 3-pointer shot Jesse Metcalfe made was real. No camera, editorial, or digital trickery was used.