While at Luke's diner, playing a game to find prospective husbands, Lorelei passes on a young man in his 20s, saying she's "not Mary Kay Letourneau." Her comment refers to the schoolteacher who gained national attention in 1996 after she, at 34, began a sexual relationship with a twelve year old student of hers; she was charged with statutory rape and sentenced to six months in jail, and prohibited from contact with the student again. Two weeks after completing her sentence in 1998, she was discovered having sex with the student in her car, and sentenced to seven and a half years for violating her parole. She gave birth to children in 1997 while awaiting her original sentencing and in 1998 while serving her second sentence. She was released from prison in 2004, and she and the student, then a legal adult, married in 2005.
For the first time, an additional arched entry from the foyer to the living room of the Gilmore Girls' house appears. No mention of the structural change is ever made; it just happens.
When Mrs. Kim asks Lane what she & Dean are studying together, she answers "Spores, Mold & Fungus". This may be a nod to "Ghostbusters" when Egon gives Janine the same answer when she asks him what his hobbies are. (I collect spores, mold, and fungus)