Scott Patterson, who plays Luke, was not hired initially as a series regular. He was only signed on for the pilot episode. Although it was only after discovering the undeniable chemistry between him and Lauren Graham that he was contracted for more episodes, and quickly became a series regular.
Liza Weil originally tested for the role of Rory and did not get the part, but the producers liked her so much that they wrote her the role of Paris Geller.
Keiko Agena (Lane Kim) was 26 playing a 15-year-old in Season 1.
In a November 2020 New York Times article by Saul Austerlitz, Kelly Bishop (Emily Gilmore) recalled that when the show started filming, Alexis Bledel (Rory Gilmore) was so inexperienced as an actor that she sometimes didn't even understand which camera she should face. Bishop said, "I remember saying to Lauren at one point, 'I love when I'm watching the show, how you're always touching her,' [and Lauren] said, 'Actually, the reason I started doing that was because I wanted to get her to her mark.'"
Alexis Bledel hates coffee, but Rory, her character, loves it. Whenever you see her drinking "coffee" in the series, she drinks Coca-Cola out of her cup.