The scene in the mausoleum Gibb's Colt .45 Automatic pistol goes from hammer cocked to hammer down. It is a single action pistol and can only fire "IF" the hammer is already back.
As all of the serial killer's victims so far have been civilians NCIS would not have the jurisdiction to take over the case. The fact that the killer attempted to murder Gibbs would allow NCIS to work the case, but in the capacity of assisting the Virginia State Police, they wouldn't be able to take over the case entirely. There are very specific guidelines about when a case falls under federal jurisdiction, and even more specific for NCIS since they only have jurisdiction over cases involving the Navy and Marine Corps. A federal agency can't just come in and take over a case whenever they want as often depicted on television.
The corpse's is covered by the usual, unconvincing prop duct tape. It appears to be just laid on the face, and clearly not stuck to the skin. This is actually essential, especially using 'live' actors: pulling duct tape off skin would be painful and leave marks or tear the skin.
At 10:42 as agent Knight is chasing a suspect and the camera pans to see them pass a Fiat 500 you can clearly see a cameraman knelt behind the car ready to capture a close up shot of agent Knight.