Continuity mistake: In the very last scene of the movie where Chris O'Donnell and Renee Zellweger are on the terrace taking their vows, Renee is holding a bouquet. In one shot it is a bouquet of pink flowers, then it changes to a bouquet of yellow flowers and keeps switching back and forth throughout the scene.
Continuity mistake: Near the beginning of the film, when Chris O'Donnells's Grandfather gives him his grandmother's engagement ring, Chris takes the ring out of the case to look at it. He is holding it between his fingers and examining it closely. We then see a closeup of Chris holding the ring in its case. When we see a long-shot of Chris right after this, he is still holding the ring in his fingers.
Continuity mistake: During the scene in the Starlight room they show the waiter open the Don Perignon. There's a wide shot where you can see the singer with Jimmy and Anne in the background. In this shot Anne takes her glass to drink, but in the next shot, the glass is still on the table, untouched.
Continuity mistake: When Jimmy breaks up with Monique and Anne is sitting behind his back, Anne and her sis are talking about her ex-boyfriend. In one close-up of Natalie, you can see that she has stacked up the left over pieces of her cake, in the next shot, the pieces are normally lying on the plate.
Other mistake: It's after he proposes to Zoe, when they're in the limo and Milo is driving. He's talking and driving, but if you look through the window, the scenery in the background is clearly not changing.
Continuity mistake: During the scene when the tough cop ex-girlfriend is beating up the suspect, her sleeves take on a mind of their own. They move up and down without being touched.