Continuity mistake: In the wedding scene, just as the band Wilson Phillips walks in to sing, Annie turns to Helen asking "Really?" with a disappointed look on her face. When the camera zooms out to Wilson Phillips, in the background Annie, Helen and the rest of the bridesmaids are seen to be happily dancing and singing along. Then the shot again zooms into Annie and Helen, where Annie and Helen have just stopped looking at each other, prior to starting to dance and sing along.
Continuity mistake: In the scene near the end of the film, when Megan goes round to Annie's house to give her a 'pull- yourself-together' talk, the pendant on Annie's necklace is hanging down onto her chest. But near to the end of the conversation it's disappeared completely and all you can see is the necklace chain. (01:40:00)
Continuity mistake: When everyone except Helen start to show signs of food poisoning in the bridal shop, Becca puts her right hand over her mouth to keep from vomiting. The camera then switches to behind her but her right hand does not appear to be over her mouth anymore. It switches to in front of her again and this time, Becca has her left hand over her mouth.
Continuity mistake: When Annie is driving on a 2 lane country road between two large fields from the bridal shower, we see Megan drive past her with the car full of puppies. The issue is that Megan was filmed on an entirely different road that has a fence, walkway, double yellow line and is 4 lanes wide - nowhere near what Annie is driving on.
Other mistake: The wedding is officiated in Illinois but the cop car is from Wisconsin.
Continuity mistake: When Annie and Helen are taking turns toasting Lillian, Annie goes up for a second time. In the close shot, she is holding the microphone in her left hand and a champagne flute in her right. The camera goes to audience, and when it is back to her, the flute and the mic have switched hands. In the next wide shot, the are back to their original position. (00:26:40)