- Mala
- Ray Mala
- Rex
- Rex
- Buck the Dog
- Buck
- Mamo Clark
- Princess Melani
- Herbert Rawlinson
- Grant Jackson
- William Newell
- Hank McGlaurie
- John Ward
- Andrew Tupper
- John Dilson
- E. G. Ellsworth
- Selmer Jackson
- Mr. Canfield
- John Picorri
- High Priest Porotu
- George Chesebro
- Draker
- Bob Kortman
- Ship Capt. Wilson
- George Cleveland
- Goebel
- Lloyd Whitlock
- Lamar
- Tiny Roebuck
- Eppa
- Tracy Layne
- Larkin
- Anthony Pawley
- Clark
- Allen Connor
- Jim Taylor
- Frazer Acosta
- Teekor
- Ed Cassidy
- Jim Davis
- Allan Cavan
- Captain of Second Dirigible
- Edmund Cobb
- Haris / Crosby (archive footage) (uncredited)
- Val Duran
- Cave Base Native Drummer
- Frank Ellis
- Rontree
- F. Herrick Herrick
- Sub Capt. Toler
- Jerry Jerome
- Wallace
- Jack Mack
- Cave Base Radioman
- Ralph McCullough
- Chemist
- Bud Osborne
- Ellis
- Eddie Phillips
- Radio Operator
- Harry Strang
- Grover
- Henry Sylvester
- Capt. Fairchild - First Dirigible
- Al Taylor
- Marco
- Herbert Weber
- Stevens
