 Don KnottsHenry Limpet | Henry Limpet |
 Carole CookBessie Limpet | Bessie Limpet |
 Jack WestonGeorge Stickel | George Stickel |
 Andrew DugganHarlock | Harlock |
 Larry KeatingAdmiral P.P. Spewter | Admiral P.P. Spewter |
 Oscar Beregi Jr.Nazi Admiral (as Oscar Beregi) | Nazi Admiral (as Oscar Beregi) |
 Charles MeredithFleet Admiral | Fleet Admiral |
 Elizabeth MacRaeLadyfish (voice) | Ladyfish (voice) |
 Paul FreesCrusty (voice) | Crusty (voice) |
| WWesley GaleMan Staring Into Window (uncredited) | Man Staring Into Window (uncredited) |
| LLeon AltonOfficer at Fleet Admiral's Meeting (uncredited) | Officer at Fleet Admiral's Meeting (uncredited) |
 Phil ArnoldShort Fisherman (uncredited) | Short Fisherman (uncredited) |
| GGeorge BruggemanNazi Officer (uncredited) | Nazi Officer (uncredited) |
| PPaul BuschSonar Man (uncredited) | Sonar Man (uncredited) |
 Al CheccoSailor (uncredited) | Sailor (uncredited) |
| CCordy ClarkGiggling Girl (uncredited) | Giggling Girl (uncredited) |
| RRoydon ClarkSailor (uncredited) | Sailor (uncredited) |
 Sayre DearingPasserby/Naval Officer at Meeting (uncredited) | Passerby/Naval Officer at Meeting (uncredited) |
| GGeorge DeNormandNazi Officer (uncredited) | Nazi Officer (uncredited) |
| DDan DowlingNaval Officer at Meeting (uncredited) | Naval Officer at Meeting (uncredited) |
| HHarold DyrenforthU-Boat Captain (uncredited) | U-Boat Captain (uncredited) |
| LLouie EliasSailor (uncredited) | Sailor (uncredited) |
| LLisabeth FieldMiss Barnes (uncredited) | Miss Barnes (uncredited) |
| LLogan FieldLieutenant (uncredited) | Lieutenant (uncredited) |
| FFred FisherOfficer at Fleet Admiral's Meeting (uncredited) | Officer at Fleet Admiral's Meeting (uncredited) |
| WWalter FriedelNazi Officer (uncredited) | Nazi Officer (uncredited) |
| GGeorge GoldenNaval Officer at Fleet Admiral Meeting (uncredited) | Naval Officer at Fleet Admiral Meeting (uncredited) |
| MMarv GouxNazi Officer (uncredited) | Nazi Officer (uncredited) |
| JJohn HaleSailor (uncredited) | Sailor (uncredited) |
| SSam HarrisOfficer at Fleet Admiral's Briefing (uncredited) | Officer at Fleet Admiral's Briefing (uncredited) |
