Continuity mistake: During the wedding reception, George (Steve Martin) is called outside to meet with the police because there are too many cars parked in the street. Notice that the police car is curbside completely surrounded by cars. In fact, the whole street is packed with cars, making one wonder how the police car got up to the house.
Other mistake: When Franc (Martin Short) is looking at the house to see the changes for the wedding and they are talking about the menu, Kimberly Williams starts with her hair in a ponytail, then for a split second her hair is half up in a barrette and then it's back to a pony tail (or vice versa).
George: Who presents this woman? This woman? But she's not a woman. She's just a kid. And she's leaving us. I realised at that moment that I was never going to come home again and see Annie at the top of the stairs. Never going to see her again at our breakfast table in her nightgown and socks. I suddenly realised what was happening. Annie was all grown up and was leaving us, and something inside began to hurt.
Franck Eggelhoffer: Uh-oh, I bring the wrong color thread. I assumed you'd be wearing a black "tuxado."
George: It is a black "tuxado."
Franck Eggelhoffer: I don't think so, babe. This tux is "nuffy" blue. No doubt about it.
George: What're you talking about? Armani doesn't make a blue tuxedo.
Franck Eggelhoffer: Armani don't also make "polyaster."