At the reception at the end of the movie, Mel's dress is clean and dry. On the beach just before, it was dirty and wet from the storm and sand.
On the beach in the rainstorm, Melanie moves in to kiss Jake with her hand grasping in his face. In the overhead shot, Melanie is throwing both her arms around his neck.
At Tiffany's, Andrew asks about Christmas in Ireland, and Melanie says it's four months away, which would mean that it's August or September. For most of the rest of the film, everyone in Alabama is in long sleeves.
When the outside of Pearl and Earl's trailer is shown, it's clearly a single wide. Interior shots show a larger, double wide trailer.
When Melanie is in Alabama at Jake's house, the leaves on the tress are starting to change color, indicating the weather is getting colder and autumn is coming. The trees in cooler New York are still completely green.
When lightning strikes sand, or sandy soil, it fuses the sand into a glass-like solid mass known as a "fulgurite." Real fulgurites are usually partially hollow tube-like structures with a granular exterior. The clear glass objects in this film likely weren't created by lightning.
Melanie wouldn't have been able to marry Andrew, even if she signed the document before the wedding. It would have to be sent to the judge handling the case, and at least one party would have to go to court to answer questions. Once the judge signs off, there is a cooling-off period of up to two months (depending on where they filed) before the divorce becomes official. If she went through with the wedding, she would commit the crime of bigamy.
If Melanie has been gone for 7 years, as she told Andrew in the beginning of the movie, then the statute of limitations would have run out on her crime of dumping the sheriffs Mothers tractor in the water. She couldn't be arrested for that.
At the fair, Melanie's outfit changes from a dress with cowboy boots to blue jeans and a jean jacket. Several hours passed between her wearing the dress (daytime) and her jeans (night). It's a small town, so she could have gone home, changed clothes, and gone back to the fair.
When Melanie's mom makes plum jam, the fruits that look peaches are smooth, yellow plums, like Chickasaw plums.
When Jake throws a bone into the lake for the dog to fetch it, the dog that emerges from the water is clearly a fake, with no natural movement.
In the graveyard, after Jake tells Melanie to leave, she bumps into a "stone" dog on top of a grave marker, which wobbles more than a loosely-fixed decoration would, revealing that it's made of foam.
When Jake drives Andrew to Melanie's house, the gear selector is obviously in park.
Jake bumps a gravestone that wiggles back and forth, showing that it's made of a light material like foam board.
When Melanie is walking to the fair, a fire truck has "Pigeon Creek Fire Department" on its door, and "K.F.D." clearly visible on the front right corner.
When Melanie is walking through the battlefield, her sound equipment is visible, tucked into her boot.
When Jake is drinking the can of light beer, the camera is reflected on the bottom of the can.
When the wedding guests are running from the rain, a camera and camera operator are visible in the top left corner of the screen.
When Melanie's father, Earl, returns home from the battlefield with Andrew, he says, "Look what I found walking down I-58". If the movie is set in Pigeon Creek, Alabama then the only interstate anywhere nearby is I-65.
Andrew Hennings says he has a Lear jet parked in Mobile. The movie is set in Tuscaloosa County, about an hour from Birmingham International Airport on a modern interstate, and three hours from Mobile on a rural highway.
Andrew mentions to his mother that they will be staying at The Golden Cherry Motel. This Motel is located in Opelika, Alabama, which is nowhere near where this movie is supposed to have taken place.
The street where Melanie is dropped off to go to Tiffany's back entrance is nowhere near the actual Tiffany store.
Melanie drives past a sign on her way home in Alabama that says "Greenville," a town about two hours from the beach. If that's near her childhood home, she wouldn't have been there alone as a child, or popped by after the wedding. If she lived near the beach, she wouldn't be driving through Greenville.
Melanie Smooter hides her "low" origins by adopting the surname "Carmichael" in New York, and that's how she's known in the fashion world. Several of her former friends in Alabama say they know of her designing career; one even says he's read stories about her on the Internet. Why would the town be so surprised to learn that she had been living as Carmichael instead of Smooter?
When Melanie's lawyer, Mr. Buford, tries to find her, he asks the townspeople if they know where Melanie Carmichael is. If Buford is handling her divorce, he would have to know her real last name, Smooter. Otherwise he couldn't get the divorce granted. Divorces can only be granted to the same persons who were married, Melanie Carmichael never existed, and never married Jake.
When Melanie is at the Carmichael Plantation to talk to Bobby Ray and Barry Lowenstein, an assistant of Kate's suddenly shows up, pretending to be a reporter when he's looking for dirt on Melanie. Melanie clearly doesn't recognize him, and is surprised to see him in Kate's limo after everyone returns to Manhattan. However, Barry was standing beside Kate when Melanie and Andrew's engagement was revealed.
When Melanie is at the Carmichael Plantation to talk to Bobby Ray and Barry Lowenstein, an assistant of Kate's, suddenly shows up pretending to be a reporter when he's actually looking for dirt on Melanie. Melanie clearly does not recognize him and is surprised to see him in Kate's limo after everyone returns to Manhattan. However, Barry was present, standing beside Kate when Melanie and Andrew's engagement was revealed.
When Melanie's parents are arguing about the volume on the television while on the phone, Pearl says, "They could have heard it all the way at Joe and Lurlynn's house." Lurlynn is married to Clinton, not Joe.
Melanie jokingly asks if the Piggly Wiggly ran out of soap. The closest Piggly Wiggly is over 100 miles from where the story is set.