When Mary is running next to the news van, cars are in a parking lot behind her including a white Toyota Camry. As she continues running, she runs past the same parking lot with the same Camry visible in the background.
When Mary falls into the hole, she lets go of the umbrella. When the station manager reviews the footage, she falls with the umbrella.
One of the many problems with Howard's car is that, "reverse doesn't work," but when we first see the car in the hospital parking lot it has obviously been reversed into its spot.
When Mary comes down the stairs after changing her outfit for her first date with Steve, much of her bra hangs out of the top buttons of her sweater. When the camera cuts, then cuts back, not nearly as much bra shows.
When Mary is helping pick up in the parking lot after Steve is on his way to Galveston, the poster she is holding changes position from shot to shot.
When the truck driver shows Mary his driver license, it's a regular Arizona operator's license, with "Driver License" in blue. A trucker's license has "Commercial Driver License" in green.
When the boy signs "lawsuit" he actually makes the sign for "again".
Howard's American Motors Corporation Gremlin has a General Motors key in the ignition.
When Hartman Hughes is doing his report on the hurricane, the ocean behind him is almost calm, despite the strong wind-driven rain.
At the protest, Mary is invited back to the media tent. As she walks through the metal detector, her pin activates an audible alarm on the detector. She walks back through the detector 4 times to take metal items off, yet the audible alarm does not activate when she walks back through, only when she is walking toward the media tent.
When the Gremlin passes the "Silver Plume Fair 10 Miles Ahead" signs, the crew are visible, including a sound boom, reflected on the side of the following cars.
When Mary leaves the hospital, the cameraman filming her walking away is holding a 35mm film camera, so he's not a news cameraman.
During the scene after the tornado in Galveston,TX there is a shot of the damage along the roadway. with mountains visible in the background. There are no mountains with several hundred miles of Galveston.
In the Oklahoma City scenes, cars are shown with tags on the front. This is not required in Oklahoma.
There is no (sensible) route from Oklahoma City to Galveston that passes through a desert.
The medical clinic is surrounded by large hills covered with pine trees and bare ground. It's supposed to be in Oklahoma City, which is very flat and on the edge of Great Plains.
On certain DVD releases of the film, the DVD menu follows the path of Mary's quest to follow Steve. The last stop is in Silver Plume, Colorado, which the menu shows to be northeast of Denver, but it's northwest of it.
If Mary knows enough sign language to understand the little deaf girl, she should have been signing to her instead of just speaking to her.