The whole episode is a reference to sports athletes and doping abuse. It could be a reference to the fact that many female athletes had strongly abused doping over the years, to the point of becoming masculine, having gotten deeper voices and more masculine features.
The outfits worn in the Butterfly Derby are a reference to the 1984 manga, Elf 17. The opening chapter features the protagonist participating in a martial arts tournaments, wearing a leotard and spawning pink butterfly wings.
The name of the arena is Monsanto Yokel Dome. In "The Series Has Landed", the Goophy Gophers Revue is presented by the Monsanto corporation.