Other mistake: After the shoot out at night the American forces are faced with a group of hostile locals, and the team are told to pull out and get in the vehicles. As they drive off we see a back shot of them sitting on the back of the one of the vehicles, but on the right hand side you can see a backpack and part of an American soldier, did they just leave him? (01:12:50)
Other mistake: Chris Kyle states age "30" when entering Seals, around the turn of the century - but he is only 39 years old when he is murdered in 2013.
Other mistake: When Chris Kyle is celebrating his daughters Birthday party at the end of the movie he comes from inside the house and out to the back yard, While he is talking to his wife and watching a dog play with his son, after a minute it looks as if the dog is attacking his son and he gets up to stop the dog. As he gets up you can see that his pants are wet and that he has grass stains on his knees from the previous takes. During the actual scene he is on his knees with a belt to stop the dog when his wife yells at him to stop.
Chosen answer: Chris has "shooter's strawberries" on his elbows, which are red callouses caused by lying in the sniper's position for long periods. He notices the same marks on the elbows of the father, and realizes that he too is a military sniper.
Sierra1