Errors in geography
A massive open air nature park is shown to be the location Westworld. This park is shown to be desert and arid mountains. Unfortunately, the area for several hundred miles around Houston is either coastal salt plains, temperate forests, farmlands or forested rolling hills. The nearest desert is hundreds of miles to the west and the closest mountain are the heavily forested Quachitas north in Arkansas and Eastern Oklahoma.
In addition, the motors to open and shut the doors would have to be accessible for repair and/or replacement. Even assuming an exceptionally low rate of failure, the motors would have to be accessible for routine maintenance and inspection , as well the inspections required for municipal codes and insurance safety inspections.
In short, while the doors could fail, that this failure would trap people behind those doors simply isn't possible.
This seems to be even more incongruous later in the film when The Gunslinger uses a rifle (a long distance weapon) to shoot and kill a park employee. Why would robots need to use or have rifles when the rifle are not supposed to injure or kill guests or park employees?