David Feiss' name appears in two episodes. In "Happy Baboon Holidays" (Season 1) it is written on a wall behind I.R.'s trailer, when we first see it. And once again, in "I Am Franken-Weasel" (Season 5) "Feiss" is written on one of the headstones in the cemetery, when I.R. goes to "get a fresh body".
The theme song of the series is a edited version of Pop goes the weasel.