 Noah Beery Jr.Jan Trevor | Jan Trevor |
 Dorothy ShortMona Andrews | Mona Andrews |
 Harry WoodsBorno | Borno |
 Bryant WashburnDr. Harry Trevor | Dr. Harry Trevor |
 Walter MillerDr. Frank Bracken | Dr. Frank Bracken |
 John DavidsonPrince Samu | Prince Samu |
 Fred MacKayeDr. Charles Phillips | Dr. Charles Phillips |
 Viva TattersallGeorgia Trevor | Georgia Trevor |
 William DesmondAllen | Allen |
 Grace CunardMrs. Camerford Amster | Mrs. Camerford Amster |
 Russ PowellHenry Andrews | Henry Andrews |
 Don BrodieDr. Carl Neff | Dr. Carl Neff |
 Harry WorthDr. Carl Neff | Dr. Carl Neff |
 Dickie JonesJan Trevor as a Boy | Jan Trevor as a Boy |
 Eddie KaneGen. Tichak | Gen. Tichak |
 Stanley AndrewsEmperor Mena | Emperor Mena |
 Richard AlexanderNavigator (archive footage) | Navigator (archive footage) |
 King BaggotDr. Pierce | Dr. Pierce |
 J. Frank GlendonSpeaker at Conference | Speaker at Conference |
 Al FergusonGuard of Mu | Guard of Mu |
 Eric MayneDoctor at Conference | Doctor at Conference |
 J.P. McGowanFreighter Captain | Freighter Captain |
 Charles MurphyGrubb, Freighter's Mate | Grubb, Freighter's Mate |
 Eddie ParkerEmperor's Guard / Mu Sentry | Emperor's Guard / Mu Sentry |
 Buddy RooseveltBatu | Batu |
 Hal TaliaferroLancer Officer-in-Charge | Lancer Officer-in-Charge |
| GGwendolyn LoganMrs. Henry Andrews | Mrs. Henry Andrews |
| HH. BurroughsKutu | Kutu |
