Re-edited feature version of serial The Phantom Empire (1935). Singer Gene Autry discovers a race of advanced humans living beneath the earth.
| Actor | Role |
|---|---|
 Gene AutryGene Autry | Gene Autry |
 Frankie DarroFrankie Baxter | Frankie Baxter |
 Smiley BurnetteOscar (archive footage) | Oscar (archive footage) |
 Betsy King RossBetsy Baxter | Betsy Baxter |
 Dorothy ChristyQueen Tika | Queen Tika |
 Wheeler OakmanArgo | Argo |
 Charles K. FrenchMal | Mal |
 Warner RichmondRab | Rab |
 J. Frank GlendonProf. Beetson (archive footage) | Prof. Beetson (archive footage) |
 Edward Peil Sr.Dr. Cooper (archive footage) | Dr. Cooper (archive footage) |
| JJack CarlyleSaunders (archive footage) | Saunders (archive footage) |
| PPeter PotterMike (archive footage) | Mike (archive footage) |