In the opening scene, Reece is seen "kissing" her daughter underwater. It was actually a case of "buddy breathing", where she was providing her daughter enough oxygen till she would get to the surface.
The device which secured the rifle in the front of the patrol car is called a console mounted gun rack, or in this case a Pro-gard Partition Mount lock made of a 16-gauge steel compostion.
DHS can take control of the scene from the local Sheriff even though the incident took place on non-Federal lands. There are a number of ways and circumstances where the Feds can take control of an incident, and one is if it involves National Security which this clearly involves and is actually stated as a reason for DHS involvement.