Continuity mistake: In the final scene of the movie when Jane gets married on the beach, you see guests arriving and Tess is handing out programs. She hands a program to a blond girl with a brown polka dot dress. In the next shot, we see Tess talking to George and the same woman arrives again and Tess hands her a program again.
Continuity mistake: In the argument in the car in the rain, Kevin has a seatbelt on, but while accusing Jane of being in a creepy love triangle, he has no belt on. When he says "Nice Jane," he has a seat belt on. It is off again when Jane says she is thrilled about the boss and sister marrying. It is on again at the road sign where Kevin doesn't have Spidy vision. When Kevin checks for a cell phone signal once the car stops hydroplaning, the seatbelt is over his collar but when he snaps the cell phone shut, the collar is over the seatbelt suddenly.
Continuity mistake: After arriving home depressed from reading the article Kevin wrote in the journal, Jane is seated on her couch beside a pillow. You can see the flower in the lower corner of the pillow, but when Tess is screaming about bridezilla, Jane has moved over and you cannot see the lower flower - but later she has moved for the viewing of the flowers again when Tess leaves.
Continuity mistake: Jane is modeling the yellow dress with red flowers and Kevin has the camera in his right hand but when he says "Oh my God!", his right hand is free to cover his mouth. Then the camera is back in his hand to take the photo. Later when Jane is sitting in the red dress talking with Kevin about things she has done for people as a bridesmaid, her necklace that was off center moves to the center. But when she says "I am Jesus" and then is back off center again.
Continuity mistake: Kevin and Jane arrive at the bar, and after Kevin announces the pay phone is dead, the bartender sets a glass down and puts his hands on the bar. But after Kevin places the scotch order, there is the sound of a glass being set down again, and a small piece of the serviette shows. After Kevin and Jane dance to Benny and the Jets, Kevin helps Jane off the stage and Kevin admits he cried at the Keller wedding. Some sweat is shown on his neck, but when Jane grabs his neck to kiss him, his neck is dry.
Continuity mistake: When the boss is proposing to the sister, one of the men who is holding the fabric sign has it scrunched up in one corner. He then drops the fabric so that it is hanging straight, but then changes between hanging straight and scrunched between shots.
Continuity mistake: When Jane is wearing one gown (from Suzanne and Greg's wedding), while carrying another in a bag, she hails a taxi and affixed on its roof there is an illuminated advertisement panel and its number is "9Z66". However, in the next two shots the ad panel has vanished and the taxi's number is now "8Z30". (There is a missing shot which can be seen in the deleted scenes. Still a mistake, but there's the reason.) (00:04:10)
Factual error: In the Monday morning shots of New York in the beginning of the film, there is a shot of the Brooklyn Bridge and the Manhattan skyline behind it. If this were actually morning, the sun would be behind the camera (East), but it appears to be behind the buildings (West) making this an evening shot. The Circle Line tour boat also goes by, which would not be in service at sunrise.
Continuity mistake: When Kevin goes to Jane's apartment, after she tries on all the dresses, they are sitting across from each other talking. Jane has her feet propped up on the coffee table. She takes her feet off the table, sits back in her chair, and sits a glass of water on the coffee table. A second later the camera focuses on Kevin, and then back to the camera shot from the side showing them both sitting there. Suddenly Jane's feet are back on the table.