Revealing mistake: During the "power outage" when Brian is out on the street during the day, all the stop lights and cross walks are on - you can also see the lighting is on in the windows of office buildings.
Revealing mistake: Near the end, you're able to see the device used to blow open the kitchen door to make it look like a bomb went off. (00:34:55)
Revealing mistake: The doctors remove a bullet from Elliot's abdomen and place it in a metal medical dish. The bullet appears to be a 9mm or a 9mm short however it has no striations. When a bullet is fired it goes through the barrel picking up the land and grooves of the bore. The bullet should have spirals, this one looks brand-new, like it was just purchased to reload ammunition. (00:48:30 - 00:49:00)