 Will HayWilliam Potts / Muller | William Potts / Muller |
 Frank PettingellProfessor Hoffman | Professor Hoffman |
 Julien MitchellGeneral Von Glotz | General Von Glotz |
 Charles HawtreyMax | Max |
 Barry MorseKurt | Kurt |
 Peter UstinovKrauss | Krauss |
| PPeter CroftHans | Hans |
 Anne FirthLena | Lena |
| LLeslie HarcourtVogel | Vogel |
 Jeremy HawkA.D.C. | A.D.C. |
 Raymond LovellSchmidt | Schmidt |
 Aubrey MallalieuRector | Rector |
 John WilliamsMaj. Bishop | Maj. Bishop |
| LLawrence O'MaddenCol. Truscott | Col. Truscott |
| JJohn BoxerBritish Pilot | British Pilot |
| CClifford BucktonMI5 Man (uncredited) | MI5 Man (uncredited) |
| AArthur DentonDetective Carter (uncredited) | Detective Carter (uncredited) |
 Leslie DwyerGerman Soldier on Train | German Soldier on Train |
| RRichard GeorgeGerman Pilot | German Pilot |
 Walter GotellSS Guard | SS Guard |
 William HartnellGerman Officer at Station | German Officer at Station |
 Bryan HerbertAirport Official | Airport Official |
| VVincent HolmanMember of the General Staff | Member of the General Staff |
 Charles PatonPassenger Arrested on Train | Passenger Arrested on Train |
| LLloyd PearsonTrain Passenger | Train Passenger |
 Johnnie Schofield1st Observer (uncredited) | 1st Observer (uncredited) |
 Harry TerrySS Guard (uncredited) | SS Guard (uncredited) |
| JJack VyvyanDetective Evans (uncredited) | Detective Evans (uncredited) |
| HH Victor WeskeSS Officer on Train (uncredited) | SS Officer on Train (uncredited) |
