Continuity mistake: When Pam is ringing Greg near the end, Jack is watching from the side, and it is obvious how much longer his hair is compared to the rest of the movie. His hair is quite short in the rest of the movie. So it is obvious (since he looks younger in that scene) that that scene had been shot near the start of the filming.
Continuity mistake: For the first half of the movie, the cat's tail changes colour from black to light brown, to black again.
Continuity mistake: When Greg is at the airport's lost luggage department you see the baby chuck up on him but you can see it actually comes from too low down. (00:08:00)
Continuity mistake: At the dinner table when Greg is trying to open the champagne, Pam look straight ahead startled for a second, then in the next frame she is talking to her dad again. It looks like she is seeing the urn hit before it is in the film.
Continuity mistake: Near the end of the film Greg is talking to Pam. She is laying on the bed and he is sitting on the bed . The scene moves back and forth from him to her and every time the pendant on her necklace moves from side to side.
Continuity mistake: Pam's hair constantly looks different from shot to shot in different scenes. For example, when they first get to the parents' house it goes from limp/wavy to ringlet-type curls from shot to shot. Also, she is wearing a lot of eye make-up in the car on the way from the airport, but once she gets to the parents' house it seems like she hardly has any make-up on.
Continuity mistake: When Robert De Niro's character is showing off the surveillance equipment inside the bear and in the room, he turns the TV on and it stays on. Later when the scene is about completed, the TV is on in one frame, and then with no-one motioning to turn it off, or having their hands near it, the TV turns off by itself. One shot it's on, the next it's not.
Continuity mistake: After the urn scene Greg and Pam are kissing and depending on where the camera is her hands are either on his cheek or more near his ears.
Continuity mistake: During the race home scene, just after noticing Jack next to their car, Larry says "Oh look, there's Jack", and his face turns back forwards towards the front of the car, but then in a split second the shot changes and Larry is looking straight to his left (when saying "Hey Jackie").
Continuity mistake: When Jack says, "You spray painted his tail to make him look like Jinxy didn't you?" Look closely at Bob behind him, his mouth is closed but in the next shot of Jack holding Jinxy, Bob's mouth is open.
Continuity mistake: When Greg and Pam arrive at Pam's parents' house, Greg opens the driver's door and the window is up. After Pam throws his pack of cigarettes on to the roof, he closes the driver's door and the window is now down.
Continuity mistake: When Denny sneaks in his window, he has on a jacket. Later on when they go downstairs, Pam gets the same jacket out of the closet for Greg to wear.
Continuity mistake: When Greg borrows Jack's P.J.'s, sometimes there are initials on them others there aren't.
Continuity mistake: When Jack is talking on the phone and Greg is on the roof, Jack is not wearing any jacket. Then just as he steps into the house you see his back and he's wearing the tan jacket.