In the opening scene, the train being robbed is the Durango to Silverton (D/SNGRR) tourist train in Colorado. It is a narrow gauge railroad that runs along the Animas River.
Final film of Joan Staley. Near the end of production, she severely injured her back when she fell off her horse. Fortunately, she suffered no permanent damage, but enough so that she thereafter only made occasional appearances on TV as long as she would not be required to do anything too physical.
Joan Staley's character is called Uvalde, but it's a nickname, as that's the Texas town she comes from. Her real name is Bonnie Mitchell.