This episode, the series finale, marks the second time Ryan and Seth share a hug. The first time was the first episode of the series.
In season 1 when the Nana first appears, they reveal that her name is Sophia Cohen. Another point in the show they reveal that Kirsten's mother's name was Rose. In the final episode when sandy is holding the new-born baby, he reveals the baby's name is "Sophie Rose Cohen".
Todd Sherry plays a waiter at one of the Newport parties in "The Pilot" and later in "The Return of the Nana". 3 seasons later he plays a completely different character, Todd, who lives in the Berkeley house that the Cohen family want to buy back. Sherry was also a casting associate on the show.
Several details in the final montage indicate that Seth and Summer have a traditional Jewish wedding ceremony, including the canopy (chuppah) under which they get married, the yarmulkes that Seth and Ryan both wear, and the glass that Seth steps on at the end of the vows.
Highest rated episode of the entire series.