On the second disc of the region 1 DVD, there's a behind-the-scene featurette that contains a clip of Eliza Dushku dancing by the van before a take. The song she dances to is "I Just Wanna Love U (Give It 2 Me)" by Jay-Z.
Soundtrack Q & A
What song is playing when the girls come out of the van at Mooby's? ...from Tony in Whittier, Ca (answer Tony's question)