When Willow talks in French to the monkey without pants during the teaser, she says "The hippo stole your pants" which refers to the conversation she had with Oz at the end of "What's My Line? Part 2" where Oz wonders if the hippo animal cracker is jealous of the fact that the monkey is the only animal cracker with pants, as well as asserting that "all monkeys are french."
Buffy asks Xander "You and bug people, what's up with that?" to which he replies "He was no Praying Mantis Lady" - refering to the substitute teacher that seduced Xander, but was in reality a praying mantis.