The Tolstoy quote Luke refers to is, "All happy families resemble one another, each unhappy family is unhappy in its own way".
Jason incorrectly refers to Luke as "Duke." In S2E15 Lost and Found (2002), Rory mentions that Lorelai used to called him "Duke" to annoy him.
Paris says to Rory, "Mary, you are such a prude." This is the first time in years Rory has been called "Mary," her nickname when she began attending Chilton, likening her to the Virgin Mary.
Paris's "Chasing the dragon" comment is often used to refer to an opium addiction.
This is the first appearance of Liz Danes (Kathleen Wilhoite ), Luke's sister, who then goes on to appear more frequently.