When Cade, Sutton and Radio man find the woman who killed herself in the car, you can clearly see her breathing several times, while they are talking near her.
During the road journey, a man hunts down a wild boar and shoots it on the left side, near the heart: on the following scene, the boar is being cooked and no sign of the rifle shot can be seen.
If a lightning struck a car there's no fuel tank explosion as suggested by Karen before escaping the town due to Faraday's cage principle.
The (possible but not even confirmed) inversion of Earth's magnetic field has nothing to do with the Sun-relative cardinal points since both Sun and Earth would still rotate as before the event.
During the car journey, the group stops and Karen says that they're without food and water and that it is a big issue: in that scene they're surrounded by snow which can easily be turned into drinkable water.
When driving in group an earthquake hits and a van is seen so much affected by this to go off road down a cliff: the intensity required to achieve this would involve devastating damage to surroundings which does not happen.
It is not explained why the group that is in haste to run away has to stop for the night and can't continue the journey on the road simply switching driver (if needed).
Despite being settled in the present days, no sign of a GPS navigation system is to be seen throughout all of the movie and all the routes are checked on a paper road map.
One of the villains constantly aims at eating human flesh because of it being their last resource of food: in the meantime they pass on by various abandoned houses that could highly likely have more standard food in them.