Teenage Mutant Leela's Hurdles - S5-E7
Factual error: When Professor Farnsworth visits the Bubbling Geezer to receive youthasizing treatment, the trained professional Heather says "botulism toxin tightens and tones facial muscles." Botulism is the actual poisoning, not the toxin. Botulinum toxin causes muscle paralysis which weakens the muscle, not tightening and toning of the muscles.