When Cassie suggests a tattoo of 'a sexy hula girl that flexes when you wiggle', she's referring to Little Pete's tattoo Petunia. Michelle Trachtenberg played Nona Mecklenberg on Pete & Pete
Willow asks if Buffy thinks Cassie is some kind of "precog," a term popularized in the movie (and Philip K. Dick novel) Minority Report, which opened several months prior to the first airing of Help