Continuity mistake: When the crane breaks, it only drops one end of the cable with the hook into the hole. However, later on Mary makes a contraption which the cable snapped and both ends are in the hole, going up over the pulley on the crane. The number of cables going into the hole from the crane varies for the remainder of the movie from 1 to 2 cables - and is not to be confused with the string of lights.
Factual error: When the TV news vehicles are leaving the hospital, supposedly set in Oklahoma, the ocean is briefly visible in the background.
Other mistake: The camera shots that Steve takes during the storm are far too steady given how much we see him moving the camera, almost as if it was on a tripod. The problem is that Steve is holding the camera and we can see how much it moves during the ground collapse footage he takes when the kids are being rescued.
Continuity mistake: When Mary first arrives at the hospital protest, she is being escorted through the metal detector by Hartman. Mary is wearing a tie-dye shirt with one blue shoulder and one red shoulder. As she passes through the detector, her ribbon is pinned on her red shoulder. The camera shoots to Hartman, then back to Mary, exposing her red shoulder without the ribbon. The camera shoots back to Hartman, then the next shot shows Mary removing the ribbon from her red shoulder and placing it into the bin so she can pass through the detector successfully. I understand how a person can sometimes confuse right from left depending on the angle of the camera. This time, one shoulder is red and one is blue, there's no confusion.
Continuity mistake: The scene where Mary, Howard and Elizabeth are running to the tunnel to escape the tornado, Mary has her umbrella open. The next shot shows Elizabeth going into the tunnel with Mary right behind. Mary's umbrella is still open. The next shot shows Mary half way down the tunnel with her umbrella closed. There is no way she could have closed that umbrella in that wind and got that far down the tunnel that fast.