Continuity mistake: Right after Clooney picks the kids up from pre-school. It was superhero day, so the kids are dressed in homemade costumes. If you watch the little girl, she changes back and forth between superhero and little girl within the blink of an eye.
Continuity mistake: When George Clooney is trying to persuade his contact to tell the truth, he's got his hands either side of his contact's face. Depending on the angle, his hands are in different positions - whether his thumb's covering an ear or not is an easy way to see.
Continuity mistake: When Melanie Parker (Michelle Pfeiffer) first appears at her neighbour's front door she is carrying a fishbowl. A few scenes later she is hurrying down the street to the school and the fishbowl now has plastic covering the top.
Continuity mistake: When Jack and Melanie are arguing and waiting for a cab to get to the soccer match, the kids interrupt them and you see a cab is waiting. The cab is a Ford Crown Victoria. They are then seen traveling in the cab, which is now a Chevrolet Caprice, which they exit before Melanie goes to her meeting for drinks.