Seth uses the phrase "You're a Cohen. Welcome to a world of insecurity and paralyzing self-doubt" to welcome Lindsay to the family. He uses the same phrase to welcome Ryan to the family in the first season (1x04) episode "The Debut".
Seth makes a reference to writing a Chrismukkah song to the tune of a song by Death Cab For Cutie, entitled "A Lack Of Color". Not only is this one of Adam Brody's favorite bands, but the song has been featured in the show before in "The Goodbye Girl".
Kirsten mentions Duran Duran's 'Hungry Like the Wolf" in this episode, when Julie's phone starts to ring.