During Gene's fart song over the end credits, Tina at one point pulls out two guitars for her and Louise to play. She begins by playing hers left handed, but when they first sing 'all that air from your own derriere', she's playing it right handed. The next time she's shown playing about three seconds later, she's playing it left handed again and continues to play it left handed for the rest of the song.
In the opening scene the Wagstaff school sign is misspelled "Waggstaff".