When John and Secretary Cleary are having cigars on the balcony at the wedding, their backs are to the camera. We hear Cleary speaking when he obviously should not be able to because he is puffing on his cigar.
During a discussion about an organic scallop farm, Claire says that they got the governor to subsidize the farm. She continues to say its the state's only "self-sustaining scallop farm", yet subsidization means that it cannot be self-sustaining.
All three daughters of the Cleary family have different hair colors. Claire (brunette), Gloria (red), and Christina (blonde), it is highly unlikely this occurred naturally, they would have no reason to dye their hair.
When the Clearly family, John and Jeremy take a trip out on the Clearly family yacht, a close-up shot of Claire shows land in the background and there is no movement. When the shot zooms out again the yacht is shown to be in the middle of the ocean and moving.
When Jeremy calls John into his office to first inform him that the wedding season has begun, John is holding a cup of water in his right hand. When John squeezes and throws the cup of water it is in his left hand. There is water on the back of the chair John is sitting on, but in the next shot, the water is gone.
When John is approaching Claire after Sack has announced, without prior consent from Claire, that they are planning to be married, he is wearing a lavender shirt in the foreground of the shot (while he is out of focus). When he is shown approaching Claire, he is wearing a dark blue polo.
When Claire and John go for their bike ride, they skid to a stop on the road, and there is a puddle in the foreground. That is followed by a shot of them riding some more. But in the next shot, they're back at the puddle, getting started again.
When John and Jeremy are having breakfast, Jeremy begins to put food on his plate and puts only a little bit on. The shot then changes to him and then back to his plate which is now loaded with food and it had only been about a second and his arm had barely moved.
When Claire first goes to check on Sack in the bathroom after he gets sick from the eye drops. She opens the door with her left hand and her right arm stays hanging. But when the camera cuts back to Claire her right hand is gripping the door and her left hand is no longer on the door knob but on the door itself. There is no way that her right arm could move that quickly to the door edge.
When Todd comes in to Jeremy's room in the middle of the night, he and Jeremy move around a lot in the bed when they hear Sen. Cleary coming. The blankets are all messed up when Todd is finally in the closet but when the camera cuts back once Cleary is in the room, the blankets are all smoothed out.
When Jeremy and the priest are sitting at the table talking, Jeremy pours him a hefty glass of liquor full to the rim. When the priest lifts his drink at the end of Jeremy's speach his glass is almost empty. The camera was on him most of the time Jeremy was talking and there is no way that he could have possibly drank that much.
When John gets up to answer the door and let Jeremy in, he places the "Don't Jump" book on the arm of the chair with the spine facing the camera. When Jeremy picks up the book, the spine is facing away from the camera.
When John and Jeremy are walking down the driveway to the ferry, Jeremy has the painting Todd gave him in his arm. In one shot the bottom of the painting is in front and in the next shot, the top of the painting is in front, allowing John to give a disgusted look.
On the quail hunt, in the wide shot showing all the characters walking forward, a person's arm (presumably a crew member's), can be seen sticking out from behind a tree on the top right side of the frame.
When Sack calls his friend to check up on John and Jeremy, he only knows their fake surname, Ryan. If Sack's friend actually checked up on those two "brothers," he would not learn that they were wedding crashers who go to weddings to meet and seduce women. There is no explanation for how Sack's friend could get the real low-down on these two individuals in such a short period of time.