The Fundamental Things Apply - S4-E5
Continuity mistake: While Lorelai and Michel are at the diner Luke tells Lorelai to take Michel elsewhere, and when Luke goes behind the counter his shirt is perfectly dry in this wideshot and following closeup. but in the next wideshot, as Lorelai tries to get Luke's attention, we now see a round wet spot on Luke's back, but the problem is Lorelai has not yet tossed the lemon wedge at Luke's back that causes the wet spot on his shirt. Lorelai tosses the lemon wedge about ten shots later. (00:07:25)
The Fundamental Things Apply - S4-E5
Continuity mistake: Lorelai is in Luke's Diner talking to Luke. Lorelai is wearing a red sweater vest over a white blouse. When Luke is behind the counter, every time the camera faces Lorelai, the left side of her blouse goes from being tucked in under the vest (as if the vest were hastily put on), to being untucked (as it should be) quite a few times.
The Fundamental Things Apply - S4-E5
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.
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.