On the envelopes from Dean, his last name is spelled "Forester". Later, in Face-Off (2003), on the back of Dean's jersey his last name is spelled "Forrester".
In The Third Lorelai (2001) Paris arrives at the Gilmore household because she is nervous about her date with Tristen and does not know what to wear. Rory helps her out with some clothes and prepares her for her date. However, Paris has a date with Jamie and panics because she supposedly has never gone on a date before. Rory helps Paris figure out something to wear and prepares her for her date.
Taylor is planning the "First Annual Stars Hollow End of Summer Madness Festival", which Lorelai replies "You finally found a way to fill September." Later, when Emily Gilmore calls Lorelai, she says it's Thursday the third. Thursday, September 3rd doesn't occur in 2002. The closest years that have a Thursday, September 3rd are 1998 and 2009.
When Rory goes to her desk to try and write to Jess, her laptop is closed. Seconds before when she's on the phone the laptop in the background is open.
When the Gilmore girls head into Sookie's house, the camera reflection is visible in the front door.