 François Couture, a reviewer for Allmusic, said that "Mystery Roach" contains multiple meanings, all of which have a connection to lyrical subject matter in Zappa's discography.These include the freshwater fish, as the Mothers of Invention live album "Fillmore East - June 1971" contained a song referring to the mud shark, a cannabis cigarette butt, which causes the character Jeff to go crazy within the context of the film's storyline, and a combed roll hairstyle, which connects the song lyrically to "Jelly Roll Gumdrop", a song from "Cruising with Ruben & the Jets".The version featured on the album is different from the version featured in the film, as it is missing small electric guitar solos by Zappa, and was not scripted as part of the film in its electric arrangement, having originally been written in three separate, unused acoustic blues-oriented arrangements.