The bedding in Paris, with the blue trim, is the same bedding Lorelai removed from her own bed in The Long Morrow (2006).
This is the lowest rated episode of the entire series.
Lucy tells Marty: " The town where Rory grew up is, like, the perfect small town. You expect Professor Harold Hill to move there and sucker everyone into buying band instruments." Professor Harold Hill is a character in the movie "The Music Man", a con-man who indeed moves to a small town and suckers the inhabitants into buying band instruments. But the inside joke is that Rory's small town IS the exact same town where Professor Harold Hill pulled that con. Back in 1962, that classic musical was filmed on the very same outdoor set (known as Midwest Street) on the Warner Brothers studio back lot. What was then "River City, Iowa" became "Stars Hollow" decades later, but the faux town looks almost exactly the way it did back in the 60s.
Zack tells Lane that they can use her sonogram of their twins for their first album cover, referring to it as "a prenatal nevermind". That is a reference to Nirvana's 1991 album "Nevermind", which infamously featured a photo of a naked baby swimming underwater.
One of the books Rory offers to take to the library for Paris is "The Norton Anthology: English Literature" eighth edition, volume E, the Victorian Age.