Other mistake: Being a three time mom, I know that the sonogram that Susanne gives Nick at the beginning could not be hers, due to the fact that she just found out she was pregnant. The babies on that sonogram are too detailed. They have to be at least 30-35 week-old fetuses. At her stage, you would not be able to make out the baby.
Factual error: When Chuck discovers the dry rot, he tells the Persons that he played 36 seconds for the Lakers in the 1986 NBA Finals. The Lakers weren't in the 1986 Finals.
Continuity mistake: Suzanne's pregnant belly goes up and down throughout the movie without any regard to her gestation. In one scene, Suzanne rests her arms on her stomach and the next "day" she's cooking in the kitchen with a flat stomach. It's as if the movie was heavily edited and no one paid attention to her.OMGSTFU
Continuity mistake: When the boy spills the milk on Nick, the milk lands below the pizza stain. A few objects then fall from the cabinet and the eggs fly onto Nick's shirt. The stain is then higher on the shirt.
Other mistake: When Nick fixes the doorbell, Kevin tests it and when he goes back to press it again, Nick pulls him back and doesn't make contact with the button but the doorbell sounds.