Major errors in geography.
How can a major company with billions of dollars and recourses like Hollywood get a simple search wrong?
Dallas is not in, or is nowhere near, a desert. Dallas, as is most of Texas, is very green and hilly. The only dry, sandy, cacti-filled, "Hollywoodified" parts of Texas are in the far west region and only take up about 10% of the entire state. Here are some pictures of the real area surrounding Dallas, as means to educate some of you.
http://www.oscarmail.net/houstonfreeways/images/i45_houston_dallas/i45_n_of%20_buffalo_with_sign_7_2004-11-28_2000.jpg
http://3.bp.blogspot.com/-MwD3f9uV8Ls/TVvk5gqDOTI/AAAAAAAABx0/ZD3zie3qEkM/s1600/South+of+Camp+Wood-600.jpg
http://unbranded-blog-media.s3.amazonaws.com/unbranded-blog-media/2014/04/formwork_driving.jpg
https://upload.wikimedia.org/wikipedia/commons/9/9a/Xvixionx_29_April_2006_Dallas_Skyline.jpg
http://live4travel.com.ua/wp-content/uploads/2015/08/32.jpg
Someone from Hollywood could've gone out to Dallas and seen this sort of greenery. Surely they saw this stuff when they actually did go out to film in Dallas, right? I'm not sure where they got the shots of dry sand, cacti, tumbleweeds, and mountains like they did in the movie, but they had to fly a minimum of 2000 miles west to find them, because none of that is anywhere near the Dallas area. The film is clearly showing Dallas as being in a desert. If they really wanted to use a desert, they should've gone with El Paso, or just gone into a different state like Arizona, New Mexico, Nevada, or even California, all of which have much more desert than Texas.
On top of that, Mulder and Scully apparently drive from Dallas to DC in a single night, which anyone looking at a map could see is impossible. Dallas to DC would take nearly a full day. I've driven from Maine to Oklahoma and that proved to be a 32 hour drive. I could be wrong about this, but Mulder does ask to be taken to Arlington and Grapevine, both of which are big locations in the Dallas metropolitan area.
Mulder later says that the secret facility was near the Texas/Mexico border, from which they drove from Dallas. Dallas is nowhere near the Mexico border and is actually on the exact opposite side of the state. The movie seems like they drove maybe 2 hours at the most, but it would at least 12 hours to any point of the Mexican border from Dallas. Texas is a massive state, the largest in the continental US.