Boy it must have really changed down there in the last few months. Been there, done that... lawless?? NO!, We flew to the area to visit the falls a few months ago, and spent a number of days wondering around the area feeling quite safe (FYI we are both retired seniors)
The Triple Fronera, the tri-boarder area between Paraguay, Argentina and Brazil, occurs at the intersection of the Parana River and the Iguazu river forming a nice "T" shape. We have been on the exact spot, on a small boat, At that location the Parana river is about 250M wide and the Iguazu river is about 200M wide. So at best the "vast lawless area is a circle about 250M in diameter and is open river space. WOW
They did have a nice shot of the Iguazu Falls in the flashes of the area, the falls being a bit west of this location but it is certainly not part of the triple frontera .
As to the surrounding area... Three towns/citIes surround the interection, one in each of the countries... So unless you get well away from the boarder, you are not in the jungle.
And then there was the mountains that would show up in some of the shots, say out the window.. Sorry, this is not a mountain area and the vegetation just looks off. More likely shot in Hawaii,
It's too bad they don't get there facts straight.