It was a random rest-stop to stretch legs and whatnot. It just so happened that they were filming at the 'park' (Hells Half Acre). It is worth a visit if you are in the area but I wouldn't go out of your way to see it if you are not already near by. FYI, for the first movie that is where a lot of the ground stuff was filmed that looks 'alien'. All of them were super cool and were happy to take a picture (long before the days of everyone having a camera phone, this was film). They seemed really nice and polite. https://en.wikipedia.org/wiki/Hell's_Half_Acre_(Wyoming)