Although Hailey is the adult aunt to the teenage Seth, in reality, Amanda Righetti (who plays Hailey) was the teen at 19 when this show aired, while Adam Brody (who plays Seth) was the adult at 24.
From this episode on, Rachel Bilson and Melinda Clarke graduate to the opening credits (even though Clarke doesn't actually appear in this episode).
Though credited in the opening credits, Chris Carmack (Luke), Tate Donovan (Jimmy) and Melinda Clarke (Julie) do not appear in this episode.
Sandy indicates they have been married for 17 years in this episode, yet they celebrate their 20th anniversary in Season 2