(at around 1h 5 mins) When Beth is in the crawl space under the hospital, she holds her flashlight sideways, casting light on the wall on her left. When they cut to show what she sees as she is crawling, the beam of light is cast in front of her. The scene cuts back and forth between the 2 views, making the mistake very visible.
(at around 38 mins) When Beth and Jack first watch the footage from the nanny cam, the bedroom door is closed. The shot cuts back to Beth and Jack for a few seconds. When it cuts back to the nanny cam, the door is open.
(at around 38 mins) When Ed Burns character finds the video disk of the kids room he holds it up and it clearly has 'KID'S ROOM' written on the disk. When he puts it in the computer the writing is gone.
(at around 22 mins) When Brian gets up from his chair at the café, his cellphone is behind his coffee cup, then the camera focuses on him, the next shot the cellphone is in front of the cup and Beth's hand.
(at around 13 mins) The murders occur in June, but when Leann is in class looking out the window, the trees are losing their leaves, as though it were fall.
(at around 28 mins) When Beth and Taylor are woken up because their cell phones (which don't have batteries in them) ring, Beth says the call came in at 7:32 PM, but the phone shows the time to be 8:32 PM.