Casting | Rôle |
|---|
| Tom Brown | 'Smilin' Jack' Martin |
| Marjorie Lord | Janet Thompson |
| Rose Hobart | Trudy Muller, aka Fraulein von Teufel |
| Keye Luke | Captain Wing |
| Edgar Barrier | Tommy Thompson |
| Cyril Delevanti | Mah Ling / Han Po, his double |
| Philip Ahn | Wu Tan |
| Turhan Bey | Kageyama [Chs. 1-5, 12-13] |
| Sidney Toler | General Kai Ling [Chs. 1-5, 13] |
| Jay Novello | Kushimi, infiltrator [Chs. 1-3, 12-13] |
| Rico De Montez | Henchman Hito [Chs 1, 4, 12-13] |
| Nigel De Brulier | The Lo-San [Chs. 2-3, 12-13] |
| Edward Keane | Hon. George Hill [Chs. 8-12] |
| William Forrest | Secretary of Internal Affairs [Chs. 8-12] |
| Jack Gardner | Captain Yoshido [Chs. 1-3] |
| Terry Grey | Shuma, pilot [Chs. 1-3] |
| Stanley Blystone | Capt. Hardigan [Chs. 5-6] |
| Herbert Heyes | Sir Cedric [Chs. 5-7] |
| James Craven | Commissioner Robert George Hardy [Chs. 5-7] |
| Alex Havier | Sanson, phoney waiter [Chs. 6-7] |
| Paul Bryar | Herr Bauer [Chs. 6-7] |
| Norma Drury | Frau Bauer [Chs. 6-7] |
| Grace Cunard | Second German Woman Spy [Chs. 6-7] |
| David Hoffman | John O. Blenker [Chs. 9-11] |
| Edward Peil Sr. | Freighter Captain [Chs. 7-8] |
| Wheeler Oakman | Freighter Mate [Chs. 7-8] |
| Frederick Giermann | Schlesser, device expert [Chs. 10-11] |
| Bert Freeman | Shimoto, device operator [Chs. 10-11] |
| Harry Strang | Honolulu Detective-in-charge [Chs. 10-12] |
