This was Buffy's first encounter with "Chanterelle", whom she later met in Los Angeles as "Lily". She later assumed the identity "Anne Steele" under which name she had encounters with Angel who didn't recognize her despite meeting her here. Under that identity, one she took partially from Buffy herself, Anne opened a homeless shelter for teens.
After Willow's nervous conversation with Buffy and Ford, Buffy says, "There aren't two of those in the world." Foreshadows "Dopplegangland" (season 3 episode 16) where there are two Willows in the world for a short time; the good Willow we know and the bad Willow she would have become had Buffy not come to Sunnydale
Ford's line "die young and stay pretty" is a reference to the line "live fast, die young and leave a beautiful corpse" from Humphrey Bogart's Knock on Any Door (1949). James Dean also quoted the line in an interview shortly before his death.
Angel's investigation into the Sunset Club and Ford could be foreshadowing of his later detective agency where he investigated paranormal events in Los Angeles. He does the investigation in a similar manner, just with Willow and Xander instead of his own team.
The trivia item below may give away important plot points.
Julia Lee makes her first appearance in this episode. Her character appears several times (first as Chantarelle then Lily, and finally as Anne, taking Buffy's second name as her own by gratitude) throughout Buffy the Vampire Slayer (1997) and also the spin-off Angel (1999). Her character even discusses the various name changes.