Mr. Garrison's novel "In the Valley of the Penises" spoofs Beyond the Valley of the Dolls (1970), the X-rated 1969 Russ Meyer movie for which Roger Ebert, movie critic, wrote the screenplay. Trey Parker was disgusted over Ebert's review for South Park: Bigger, Longer & Uncut (1999), citing 'Beyond the Valley of the Dolls' as a reason Ebert should have been more positive in his review.
Cartman sings a song consisting solely the word "no". This song is in the tune of "Comedy Tonight!" a song from A Funny Thing Happened on the Way to the Forum (1966).
Cartman and Kyle both have AB negative blood. Of the eight main blood types, this is the rarest in the world.
In the scene where the boys visit the sick Kyle in his bedroom, his mother Sheila Broflovski mentions Kyle has diabetes. This is never mentioned again in the series, even after the introduction of diabetic child Scott Malkinson.