Hancock filmed them at Calavares and Medina. He was from San Antonio so it was convenient. The flat lake with reeds is Calavaras, a 1,200 acre power plant lake east of SA, Medina is West between I 10 and Hwy 90.
The dude in the champion jacket was a radio announcer buddy of Don's. He did a good job reading the script on something he had no clue about. I guess something like we see today.