When Behrooz and Tariq are in the desert burying the body, Tariq brings a gun with a silencer. When he shoots the gun as it is being knocked out of his hand we also hear the silenced gun shot sound. The gun on the ground shown next has no silencer. The silencer couldn't have fallen off because it is threaded onto the barrel.
Jack's soft armor ("level 3a") vest would not have stopped a rifle round from the terrorist's AK. Soft armor is only rated for pistol calibers. Even if it miraculously had, he'd have one or more broken ribs and not just pop back up and rejoin the fight right away.
During the rescue, a Marine throws a grenade into a room without checking first for any civilians including Audrey.