The $1 bill Mrs. Watts uses to pay for the bus ticket was a Federal Reserve Note. These weren't issued until 1963. In 1947, all $1 notes were Silver Certificates.
The statement about the location NOT looking like the Montrose neighborhood of Houston is NOT accurate. People who have lived in Houston know the Montrose neighborhood, among others, has houses built on man-made banks to protect property from floods. Although the scene was filmed in the Dallas area, the street and the houses on banks look exactly like Montrose. All of Houston is NOT flat.
When Mother Watts is at the bus stop and the bus approaches, the head-sign says Montrose, which is just west of downtown Houston.The terrain is sloped, not true rolling hills but still somewhat hilly. Houston is flat as a board. These hills suggest the Dallas/Irvine area.