Around 12 minutes into the episode, while Rory is just beginning dinner with Lorelai and Christopher, we see her serving salad from the bowl onto her plate. Though she is wearing a thinly strapped black dress in the scene, when the camera cuts to Lorelai and Christopher, we see Rory's arms reaching to serve more salad, and the person has blue sleeves, like they are wearing a blue sweater. This scene appears to have been shot multiple times with the characters wearing different costumes, and as another person already pointed out, there are inconsistencies with Rory having no salad on her plate right after serving herself.
At dinner, Rory grabs a bit of salad and sets it on her plate. In the next shot, she grabs salad and puts it on her empty plate.
Lorelai and Christopher both state they got married while in France. To be married in France, one of the parties to be married must reside in France for at least 40 days immediately preceding the marriage.
When Lorelai and Christopher tell Rory that they were married in France, they state that they did it in a "little church" and Christopher makes a comment that it was performed in French so he is not sure if they are legally married. As the only legal form of marriage in France is one performed by a public official (often the mayor in a small town), any marriage that was performed solely by a clergy would not be legal. The common practice in France is to be married at the town hall the day before the church ceremony.
When Luke is talking to April about "juggling" at the party, you can see the reflection of the crew in the toaster behind Luke.