Goofs

While walking through the forest near the beginning, Anthony Mackies M4 rifle has no carry handle, when they turn towards the horses in the next shot you can see that it is now equipped with one.

When Anthony Mackie is trying to restore power to the ski lift you can see a power level in the upright position behind him. When the camera changes angles it is in the down position.

When the scientist first attempts to create a 'magic bullet' in the lab, they place the round in a magazine wrong way, load it into the weapon with bullet facing wrong way, and fire at the target.

The elevation line does not follow the elevation of the terrain. Actually, in many scenes, you can see it going up and down on the terrain.

In the makeshift lab in the mountains, Nina loads a round into an AR15 magazine and puts the bullet in backwards then inserts the magazine into the rifle, racks it and shoots it at the armor of a Reaper.

After 3 years, the battery in the truck would have been dead. A lead-acid car battery can typically sit unused for 6-12 months before it is below a useful charge level.

After 3 years, the gasoline in the truck would have become unusable. Regular gasoline has a shelf life of three to six months, premium or high-octane fuel should last close to nine months, while diesel can last up to a year before it begins to degrade. The gas in the truck had been sitting for 3+ years.

When Will lets go of Katie's hand and she falls from the chairlift, the place where she lands on her back is clearly made of collapsing material to cushion the shock of her fall.

When loading the rifle magazine in the beginning, Nina inserts the top round backwards in the magazine, then loads the rifle. The rifle magically fires the backwards round, and the round which magically exited the barrel leaves no impact marks on the metal target, but sparks implying an impact.

At the end of the movie they are looking into space through a telescope. When it cuts away to show them standing by the telescope the wrong end is pointed up towards space. It's the closed end with the mirror. You can clearly see that it's closed and there are 3 screws that adjust the mirror. Light from space comes in the other end which would be open. And the viewfinder is always by the top open end.

In the beginning of the movie when Nina (Morena Baccarin) is testing out new ammunition she loads the magazine with a cartridge in the wrong direction.

The atrium in the hospital has dirt, sun, trees on the ground floor, 5th floor, and 6th floor. 5th and 6th floors should not have the ground. Just light.

As the pickup truck enters a 'deserted' Denver on the right side of the screen, several vehicles are visible exiting the scene on the left side.

The truck they use to drive down into Boulder has been sitting unused for three years but is spotlessly clean. Not even a leaf has landed on it.

Nina states the Reapers track their prey via the Carbon Dioxide their prey expels, as is shown in the mine scene. Cars do not produce Carbon Dioxide; they produce Carbon Monoxide! Therefore there is no way for the Reapers to track them when they're driving, and yet, they do.