The official flags of the San Antonio World’s Fair were overseen by the Fair’s Special Events department. Several years ago I have the privilege of corresponding with Mr. Charles Snyder who was the dept. manger.
During the six month run of HemisFair all the official flags for the Fair: SAF, National, Corporate , etc… were fabricated by Annin Flags & San Antonio based Dixie Flags.
Below are some images of the one flag I have in the archive. (Click on image for a closer look)
Below is an image from another collector who has one of the ceremonial flags from the Fair. Photo courtesy of Justin Ivy.