The charger that drives around representing 15yrs ago has a vinyl roof. The charger in the back of the automotive garage rusting away is a hardtop.
Near the beginning, Joanna skids to a quick stop onto the shoulder to investigate the odd music. The shoulder is a full shoulder, completely paved and her truck fits on it completely. She gets out of the truck and walks backward and is always on a solid surface. However, when she awakens, the shoulder is noticeably narrower. Only the drivers side tires are actually on pavement. The rest is just dirt.
When Joanna's truck goes off the road near the end of the film, the engine revs as if the drive wheels have left the road, but her pickup is a rear-wheel drive vehicle and the rear wheels were still on the bank.
When Joanna drives through the salt flat of Texas, the shot has been reversed. Most notably, Guadalupe Peak in the background is inverted.
The town of La Salle, Texas, as depicted in the movie, does not exist. La Salle is in Jackson County, Texas 77969, it is an unincorporated community with a population of only 103 people in 2000.