Creator Backlash: Trey and Matt mentioned in commentary on one of the South Park DVDs for season 3 that they considered season 2 to be very poor (explaining the lack of commentaries on the season 2 boxset), and are also mentioned to have disliked the South Park video games made early on in the show's run.
Trey is an admitted Japanophile. The South Park episode "Trapper Keeper" directly parodies Tetsuo's meltdown in Akira, and "Good Times With Weapons" is an Affectionate Parody of ShonenAnime like Fist of the North Star. He went a step further and married a Japanese woman.
The show is also full of references to Star Wars and Star Trek, and both Parker and Stone are avid video gamers (hence the show's unusually detailed and accurate references to video games and game consoles).