Lorelai's Graduation Day - S2-E21
Continuity mistake: When Rory visits Jess she has a cast on her left arm from the car accident, but while Rory's on the bus returning from her trip the cast has vanished, then the cast reappears when Lorelai gets home after graduation. (00:33:15)
Lorelai's Graduation Day - S2-E21
Continuity mistake: When Emily, Lorelai and Richard are going to take the picture, Richard lifts his arm as if he is going to put it around Lorelai's shoulder. The angle changes and his hand is no longer raised. He then raises it again before finally lowering it.
Lorelai's Graduation Day - S2-E21
Continuity mistake: When Rory and Lorelai are talking in their kitchen, Rory pushes the cafetière plunger down but then over the conversation it is pictured sometimes raised, and then lowered and then raised again a few different times. (00:04:30 - 00:06:00)
Chosen answer: Lorelai and Christopher get married impulsively in Paris but they get divorced shortly after returning home. I don't know the exact number of days or weeks but they definitely weren't married for more than a couple of months.