Other mistake: Though I love the 21st birthday at the casino plan, it's flawed. Rory will not be able to play blackjack until she is 21. She can't be playing when she turns 21. Casinos, to the best of my knowledge, won't let you on the gaming floor unless you are 21. She has to turn 21 first.
Continuity mistake: When Luke knocks on the kitchen door (at the back of the house) and calls Lorelai out to talk on the back porch, Lorelai grabs the doorknob to go out that door, but in the very next shot from outside Lorelai is actually walking out of the side living room door which is at the side of the house while Luke is standing there. Two completely different doors, at different sides of the house, and the back porch is not connected to the side/front porch. (00:06:10)
Visible crew/equipment: When Rory gets the photo album from her mother's bedroom and shows her grandparents, just as Emily reminds Richard about getting the baby dress in London, a piece of filming equipment can be seen at the right side of the screen. (00:27:25)
Continuity mistake: When Lorelai and Luke are in Luke's Diner to choose the color for the walls, Luke turns around the 'closed'-sign on the door. In this shot the venetian blind at the door is quite messed-up; partly closed, partly opened. In the following shot, where all the people are standing outside Luke's Diner looking through the windows, the venetian blind is orderly and completely opened.
Continuity mistake: In the first scene when Dean brings pizza and they are discussing about Donna Reed, in one shot Lorelai is opening the pizza box and she and Rory take a piece and start eating while they are talking. In the following shot, the piece of pizza in Lorelai's hand is gone and Rory takes a piece from the box - you can see that the pizza is complete again.
Visible crew/equipment: When the new maid tells Emily the dinner is ready even though it's only 6:30, Emily concedes and they all head to the dining room, and just as Emily says they all can be in bed by 9:00, the boom pole and mic can be seen in the living room behind them, at the top of the screen. (00:33:20)
Visible crew/equipment: After Emily tells the new maid it would wonderful to remember the difference between the bells, as Emily, Lorelai, and Rory walk away from the front door, the white, red, yellow, and green tape marks can be seen on the floor behind them. (00:32:00)