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 you can see that 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 trough the windows, the venetian blind is orderly and completely opened.
Other mistake: When Rory returns from being stranded overnight in Hartford, she comes up the walk and meets Lorelei on the porch. Although it's snowing significantly in the background, there is not a single flake of snow on Rory's hair, jacket, or backpack, and her hair is completely dry.
Plot hole: In the episode when Jess arrives at Luke's, Luke explains to Lorelai that Jess' father walked out on his family two years ago. Jess is 17 at that point, which would make him 15 when his father left. In the episode where the father comes to see him, Luke asks him why he left when Jess was just a baby in diapers, and indicates that he hasn't seen him since.
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.
Continuity mistake: Lorelai and Sookie take some containers out of the car and head towards Emily and Richard's door. When you see the next shot of them at the door, the containers Sookie is carrying are different from the ones she took out of the car, without her rearranging them.
Continuity mistake: When Rory comes into the room to answer the phone and sees Paris avoiding the call because it's her boyfriend Jamie, she empties the contents of her school bag onto the desk, including her mobile phone. Then later in the scene when Rory suggests Paris use her mobile phone to call Jamie, she pulls it out of her bag again, despite having left it on the table all but half a minute earlier.
Other mistake: Rory asks Emily for baby pictures of Lorelai, but Emily says Lorelai burned them all because she had such a big head when she was little. But in "Love and War and Snow" earlier in the season, Emily, Richard and Rory looked at a baby picture of Loralie in a bunch of petticoats the night Rory stayed over with her grandparents during a snowstorm.
Continuity mistake: After Rory is walking with Dean, it goes to a shot of Rory and Lorelai eating at Luke's Diner from outside. Rory is wearing a light blue sweater and Lorelai has a black shirt on. Then it goes inside the diner and Rory is wearing a dark bluish/grey sweater and Lorelai is wearing a purple shirt. The first shot is used from the very last scene of the episode.
Factual error: Lane wants Rory to talk to Dean about setting up Lane with his friend Todd. While asking Rory to do this, Lane asks for the date to be planned for the following Sunday, after church; however, Lane is Seventh-day Adventist and they believe the Sabbath is Saturday and therefore attend church on Saturday, not Sunday.
Continuity mistake: When Rory and Lorelai are testing cakes for the wedding at Fran's bakery, Rory is seen taking pieces out of the raspberry cake several times. However when the angle changes you can see that the cake is whole as if none of it had been eaten.
Continuity mistake: Dean calls Rory, and towards the end of the conversation mentions getting his first cell phone. This is false. He's had a cell phone the whole series. Paris even calls it in the season 2 episode "Can't Get Started" when Rory and Dean are at Sookie's wedding.