Continuity mistake: In the scene after Liv and Emma have stopped brawling, Emma's hair changes in how messy it is between shots. (01:13:50 - 01:16:10)
Visible crew/equipment: When Emma goes to crash Liv's wedding ceremony, as she crashes through the glass doors you can see film crew reflected in the glass panes.
Continuity mistake: When Liv is cake testing/trying she gets up and walks over to a table with a mouth full of cake. Yet the direct shot afterward she is talking with no cake, and begins eating a chocolate.
Continuity mistake: After Liv finds out Daniel has not been sending her the treats, she leaves the bedroom wearing purple socks. The next shot shows her walking to the kitchen with nothing on her feet.
Continuity mistake: When Emma is in the room with Deb, just as Emma is about to start shouting at Deb - Deb goes from holding the champagne, to holding her makeup, back to the champagne, and then her makeup again.
Continuity mistake: When Liv goes to get get her proposal from Daniel, between shots her hair changes in both dampness and how wavy her hair at the front is.
Continuity mistake: Nearing the end of the movie when Emma is waiting in the room with Deb, the position of her veil changes a few times.
Other mistake: When the girls go meet Mrs St Claire and schedule their dates as they are leaving they tell the other bride walking in that there is 1 date left available in June at the Plaza. Mrs. St. Claire would've told that bride the last remaining date was June 6th. Therefore, if Angela messed up the bookings hen the other bride would've already thought her date was in June 6th, and then she would not have disagreed to changing the date, because she'd be changing it to the date she originally thought she had.
Continuity mistake: In the opening shot when Emma and Liv are little girls playing dolls - Emma holds up a b/w photo of her mom and dad getting married. Later when Liv picks her Vera Wang dress, Emma says she'll get married in her mom's dress. However, before Emma's wedding her dress is completely different from the photo and Emma's mom actually comes into the bridal suite and says, "OMG is that my dress?" and Emma nods yes.
Continuity mistake: When Deb is having a drink test of wine you can see the tag is white but in the next shot the tag is brown then back to white.
Visible crew/equipment: When Liv and Emma are at their appointment with Marion St. Claire, the sound equipment above Marion's head is visible, then it rises out of shot.
Continuity mistake: When Emma meets Liv jogging in the park the day after getting engaged, the ground is very wet and has many large puddles. When Liv runs off to her boyfriend's office, the ground is absolutely dry.
Continuity mistake: When Emma runs to jump on Liv at her wedding, there is a shot of Liv and Nate, which shows Nate turning around to look at Emma. However, a further away shot then shows Nate turning around again after he has already done so.