After the Taliban recapture the woman from the village, the remaining soldiers leave and walk out along a ridge with the sunset showing their profiles. There are 5 people walking, when only 4 soldiers remain.
When the supply trucks are initially leaving the base for the re-supply mission - it shows that one of the trucks clearly only has 1 person in it (the driver). Later on when each of the two supply trucks are destroyed, they both now have two drivers.
When the marine fires a 40 mm grenade from his rifle directly on a nearby Taliban fighter at the village, it is not supposed to explode since the fuse becomes activated only after 40 yards as to protect crews from accidental firings.
The sights used on the M4s are Israel Meprolight MOR sights not used by any USMC Units.
When the remaining team members just begin to start their way to the village, they come under fire from a sniper. They hear the sniper bullet sound first, then we hear the bullet scuffing by something next to them. Bullets from snipers like that travel double and even triple the speed of sound. This would never be heard/experienced like this.
The convoy of four vehicles are driving down a road which may be in enemy hands with possible IEDs yet the vehicles are less than 10 feet apart. In this situation, an explosion on any one of them would damage at least two of them. There should be more separation between each vehicle.
Major Gavin wears his sleeves rolled up. U.S. Marines do not wear sleeves rolled up during deployment.
When Corporal Merrimette is in hand to hand fighting with the Taliban fighter he strikes the fighter in the head with a rock. He then drops the rock into the water. As the rock hits the water you can see it bounce and float (indicating it is foam).
In the intro scene, after the staff sergeant is killed, you can see his chest go up and down signalling he is still breathing.
One of the Humvees in the movie is seen carrying the M1919 machine gun on top, a weapon that was phased out in US service decades earlier. Additionally it is referred to several times as a .50 cal, in fact it is a .30 cal, during the scenes where it is fired the sound is from a .50 cal however.
Non-Commissioned Officers (NCOs) are addressed incorrectly throughout the movie. No branch of the US military addresses NCOs as "Sir" and the USMC, especially, always addresses NCOs with their full title, e.g. "Staff Sergeant" and never just "Sergeant".
When the convoy gets trapped by the ambush, you can see several of the Marines have grenade launchers on their rifles. Not one person launched a grenade which would have made a huge difference on persons living or dying.