When the tornado warning is being announced on the radio in the gas station, the announcer says it is the National Weather Service in Morristown that has issued a tornado warning and proceeds to list the counties of Anderson, Knox, and Morgan. This is in East Tennessee and NOT West Texas.
The U. S. flag in the storm tours garage is hanging improperly. When displayed against a wall, whether in the horizontal or vertical orientation, the union (stars) should always be in the upper corner, on the viewers left.
After the gorilla hail incident, glass falls from Zane's hat, but the sound is not that of vehicle window safety glass. It tinkles, more in line with the thin glass of a wine glass.
When William first meets Uncle Roy and they go to pick up folks, the Texas flag on the Turquis pickup is upside down.
00:41:29 - Lightning effects clearly visible in the tail light.
At 12:18 when Will is searching the web for info about his dad, one of the search returns (upper left corner) has an image titled "Strom chaser Bill Brody".
The movie opens saying that it takes place in West Texas, but their television is playing a broadcast from News 9 out of Oklahoma City. The meteorologist mentions Geary and Kingfisher, both of which are northwest of Oklahoma City.
After William's girlfriend and his mom meet up with Roy at the restaurant, there are several storm chasers, including Zane's tour van lined up to take photographs. Notice the Interstate sign is I-90. I-90 runs through Illinois, South Dakota, and Utah which is nowhere near Texas.
While the team is supposed to be in Nebraska near Imperial, there are two shots of an interstate 90 sign. Clearly this is because the movie was filmed in Montana. Interstate 90 obviously doesn't go through Nebraska. Interstate 80 would have been the closest interstate.
The move has William and Quinn living in Tallahassee, Florida as shown with the address of the package that was sent and explains why palm tree is shown outside the high school window However, when William is on the roof of the school looking at the storm, you see mountains. There are no such mountains like that in Florida, let alone Tallahassee.