I must admit that I'm not cognizant of the criteria for believability in a movie, whether it's in relationships or chase scenes. When the convention of the hero being shot at and inevitably missed first sprang up, it took only five or six shots to convince us that he must be dead and the bad guy out of ammo. As we've become desensitized, we require thousands of rounds from automatic weapons for the same effect, but even though we know how the scene will end, those shots still raise our anxiety. So why not computer-generated ants?
A movie, particularly a genre movie, is a balance of convention, surprise and what the viewer brings to it. I bring a penchant for seeing symbols and subtexts where others tell me they are not, a dollop of New Mexico, and a tiny bit of shared history with Harrison Ford.
The movie's first scene was shot down the hill from here (you can see the distinctive Ghost Ranch cliffs in the distance in my photo), leading to the "Nevada" test site, which I think was located on the other side of these mountains. That gave me another of those disconnections that come from being too familiar with the scenery, so I'm not sure that the guys in the trucks in the first scene were the Russians in the next. But that was okay, because the gate really did look like the gate to the Alamogordo test site in New Mexico, where the first nuclear test was done, and my friends who have seen nuclear tests tell me that this one was very accurately portrayed. (Is that a spoiler? Maybe I should put a jump here.)