Other mistake: When Meg Ryan is getting out of her black Lexus in front of her house (about 8 minutes into the movie), you can see that it is late in the afternoon by the shadows of the bushes and the trees being cast on the ground. However, she's rushing into the house to throw a 12:30 luncheon. If it were actually 12:30, the sun would be high in the sky and there would be very little shadows cast on the ground.
Continuity mistake: When Sylvia goes to Eddie's apartment to take her to Mary's lunch and she knocks the number on the door is 10C, inside the apartment it changes to 1.
Continuity mistake: When Meg is eating sugar, chocolate and butter, between shots the sugar jar's cover is on and then off, and another container vanishes.
Edie Cohen: It was so amazing, and we're so proud of you. And I am so sorry that I won't be able to stay longer to help you celebrate. But my water just broke.
Barbara Delacorte: Everything was wonderful, Mary. I must have the name of your caterer. So yummy.
Mary Haines: Oh, no. I made everything myself. I think people appreciate the personal touch.
Barbara Delacorte: You cooked? Oh, Mary, how could you. What were you thinking? Now we'll all have to do that.