Revealing mistake: When the Hårgas begin eating their meal after Dani is crowned May Queen, there is a shot of Dani just after the Hårgas pick up their knives and forks where she is looking over at Christian. Sitting next to her is a woman who cuts her food with a knife and fork, raises the fork to her mouth and takes a bite, but there is no food on the fork. She is just miming the actions. (02:13:15)
Revealing mistake: At the start when they're clearing the White House field Little Rock shoots her gun without her finger on the trigger. (00:04:20)
Revealing mistake: The helmets the soldiers are wearing are made for airsoft/paintball players. No military would issue soldiers with helmets that had holes in them for field duty, as that could allow bullets or shrapnel to penetrate the soldiers' skulls.
Revealing mistake: When Nathan and Theresa are talking on the front porch, the background is fake (and mostly blurred). The white picket fence just doesn't look real. A hanging plant on the porch sways a little from wind but the two nearby trees (leaves/branches) are stationary. Next, one tree gets a gust of wind while the other one does not and the remaining trees in the background do not show any movement. (00:13:50)
Revealing mistake: The headlights on Hayley's car are fake (i.e, blocks of white to represent headbeams). (00:30:36)
Revealing mistake: The structure/set-up of Richard's house (front view) doesn't make sense and can't be real. The half of the house to the right of the screen is at an awkward angle and has no windows. What little of the roof that can be seen is flat - not conducive to snowy Massachusetts. The bottom of the door to the right of the garage door is inches above the driveway pavement (elevated with no step). The deck wall to the right of the yellow door is higher than the door but the front rails only reach halfway. (00:03:25)
Revealing mistake: When Tree kills herself by throwing herself out of a plane, in the shot where she lands in front of Carter and Danielle, it's very blatantly obvious she was filmed on a greenscreen and comped in. The lighting on Tree doesn't quite match the lighting of the scene, and there are very obvious and unnatural hard lines around her hair where the background was rotoscoped/keyed out.
Revealing mistake: When the zombie crawls into the hardware store breaking through the bottom part of the barricade, you can already see on the wood plank the line where the wood is supposed to snap in half. (01:05:20)
Revealing mistake: She is driving and puts her phone down, you can see that car shifter is in park instead of drive.
Revealing mistake: It was pouring when Adam, Hannah, and Megan got out of their SUV to talk to the Man and try to get help with the flat tire. As they stood there, no "rain" was hitting them and it became obvious that their partially wet-looking clothes were "pre-wet" - they returned to the SUV with the same amount of "wetness." Also, the rain was coming down in straight streams, all parallel. (The water flow appeared to be slightly angled to make the artificial "rain" look more natural).