Monsters

An indie science fiction film that follows two Americans stationed in Mexico trying to make their way through the infected zone to get to the U.S. The infected zone is the northern half of Mexico filled with squid-like aliens.
Ok, so my first question is: What is up with the scene where they are both sitting on top of a pyramid admiring the U.S. border? Mexican pyramids are on the south of the country, so that was WAY OFF! Is it because everything is fiction? Or is it because the director wants the viewer to see how beautiful Mexico can be? Or is it just a mistake? I don't know...
To me, this was an immigration analogy. So, should I be offended because apparently Mexicans are monsters or feel complemented because at the end they show the human side to the aliens? I'm not really sure what to feel. I'm not really comfortable with the Mexican/alien metaphor, but I guess in the technical side of things it has excellent photography and all the extras were locals, which made the movie more authentic. I admire the fact that is was a well done film with a very small budget but I think it could have been so much better.