Continuity mistake: When Burns first shows the team the nerve tonic, the "&" on the 'Brain & Nerve Tonic' label is facing backward, but as Burns pulls it away it faces forward. Then as he moves it around as he's talking, the "&" switches between facing forward and facing backward again. This happens all in the one shot.
Audio problem: When we see Steve Sax driving, he says "What a nice little town" but his lips don't move.
Other mistake: Marcia Wallace is credited as a special guest voice even though Mrs. Krabappel's role was cut. (00:29:00)