When Lorelai is looking at pictures of Harvard valedictorians she fixates on the graduate from 1990. This could possibly be because 1990 is the year that Lorelai would have graduated college had she gone, but Rory was born in 1984 when Lorelai was 16.
A picture of comedian Anthony Jeselnik can be seen on the wall of Harvard valedictorians; class of 1985.
While "touring" the campus, Lorelai reads Harvard trivia to Rory, including the fact that Fred Gwynne who played Herman on The Munsters (1964) had attended school there. Edward Hermann, who plays Richard Gilmore, played Herman Munster in the 1995 movie Here Come the Munsters (1995).
Masi Oka has a quick role debating with Rory in the Harvard classroom. Milo Ventimiglia (who plays Jess, Luke's nephew) is introduced in this season. Masi and Milo later co-starred in Heroes (2006).
Nancy Lenehan, who plays Ladawn, the Bed and Breakfast owner, also played Pat in one episode of "Buffy the Vampire Slayer" (1997). Coincidentally, Susan Ruttan, who appears as a guest at the B&B in this episode also appeared in an episode of "Buffy" as social worker Doris. They both join Danny Strong (who later plays Doyle) as actors who appears on both shows. Danny Strong played recurring character Jonathan on "Buffy" in multiple episodes throughout the series' seven year run. In at least two episodes of "Gilmore Girls", Rory makes references to "Buffy" and mentions being a fan of the show.