Roddy McDowall really loved Thunderhead but he hated Flicka. He said she was mean and kept stepping on his foot.
The first feature film to be photographed entirely on 35mm color negative film, in this case Technicolor Monopack. Earlier color features used black-and-white negative film photographed behind color filters, or used Monopack only for certain sequences.
"Lux Radio Theater" broadcast a 60-minute radio adaptation of the movie on
February 25, 1946 with Roddy McDowall, Preston Foster and Rita Johnson reprising their film roles.
Thunderhead: Son of Flicka (1945) was shot on location at various sites, including the following:
Oregon: Bridal Veil Falls at Oneonta Gorge and the Multnomah County Fairgrounds near Gresham, Oregon
California: Brent's Crags, Hidden Valley, and Hollywood Park Racetrack
Utah: Zion National Park, Kanab, Bryce Canyon National Park, Red Rock Canyon, Navajo Lake, Glendale Gorge, Cedar City, and Cedar Breaks National Monument.
Additional scenes were shot in Duck Creek, Nevada.
California: Brent's Crags, Hidden Valley, and Hollywood Park Racetrack
Utah: Zion National Park, Kanab, Bryce Canyon National Park, Red Rock Canyon, Navajo Lake, Glendale Gorge, Cedar City, and Cedar Breaks National Monument.
Additional scenes were shot in Duck Creek, Nevada.