Goofs

When Gloria is tending to Jeremy's knee in the bathroom after the touch football game, she unties her shirt when she straddles him. Throughout the scene, the shirt reties and then unties itself.

When Jeremy is first tackled during the football game, he gets a small grass stain on his sweater right in the middle of his chest. In subsequent shots the grass stain disappears.

When Gloria is tending to Jeremy's football injury to his knee she is getting her supplies off of a cart. When she gets on Jeremy's lap there is no cart.

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 Gloria and Jeremy have their "moment" on the beach, they show them on a blanket. But neither of them are carrying one on the way there.

At the Jewish Wedding when John feigns crying by putting eye drops in his eyes, the cap is obviously still on the Visine bottle.

There are two different footballs in the football scene. The ball changes between the close-up of the snap and the ball in someone's hand and in play.

At the end after Jeremy and Gloria's wedding, the four drive off and discuss crashing some other wedding. They should just go to their own reception.

During the last wedding, when it cuts to a wide shot and the priest is talking, his mouth isn't moving.

When Jeremy is begging Todd to let him go to sleep, you can hear Jeremy talking but when we cut back to his face, his lips aren't moving.

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.

The grandmother fires the the shotgun in the house but we don't hear the bullets hit anything. Since she didn't hit Jeremy, she had to hit something (wall, window, furniture or art).

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 Claire sneaks down the hall in the middle of the night to John's room, John is sitting on his windowsill and you can see a camera in the window behind him.

After the sailboat trip, a scene shows John (Owen Wilson) and Clare (Rachel McAdams) walking along the Atlantic Ocean and sitting down on the beach. The movie was filmed in St. Michaels, Maryland, which is located on the Tred Avon River. The Atlantic Ocean is 87 miles away from St. Michaels.

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.

At the dinner table for the first family dinner, the Senator, when about to make reference to Jeremy's dancing at the wedding, calls him "John".

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.

While hunting John says that John and Jeremy have known each other for 17 years, then when Jeremy is in John's apartment Jeremy says that they have been friends for 16 years.

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.