 Gene BarryClayton Forrester | Clayton Forrester |
 Ann RobinsonSylvia Van Buren | Sylvia Van Buren |
 Lewis MartinMatthew Collins | Matthew Collins |
 Les TremayneGeneral Mann | General Mann |
 Frank KreigFiddler Hawkins (uncredited) | Fiddler Hawkins (uncredited) |
 Vernon RichRalph Heffner | Ralph Heffner |
 Sandro GiglioDr. Bilderbeck | Dr. Bilderbeck |
 Ann CodeeDr. Duprey (uncredited) | Dr. Duprey (uncredited) |
 Robert CornthwaiteDr. Pryor | Dr. Pryor |
 Cedric HardwickeCommentary (voice) | Commentary (voice) |
| HHouseley Stevenson Jr.General Mann's Aide | General Mann's Aide |
 William PhippsWash Perry | Wash Perry |
 Jack KruschenSalvatore | Salvatore |
 Paul BirchAlonzo Hogue (uncredited) | Alonzo Hogue (uncredited) |
 Paul FreesSecond Radio Reporter / Opening Announcer | Second Radio Reporter / Opening Announcer |
 Henry BrandonCop at Crash Site | Cop at Crash Site |
 Peter AdamsPine Summit Fire Watcher (uncredited) | Pine Summit Fire Watcher (uncredited) |
 Eric AldenMan (uncredited) | Man (uncredited) |
| HHugh AllenBrigadier General (uncredited) | Brigadier General (uncredited) |
| RRuth BarnellMother (uncredited) | Mother (uncredited) |
 Edgar BarrierProf. McPherson (uncredited) | Prof. McPherson (uncredited) |
 Russ BenderDr. Carmichael (uncredited) | Dr. Carmichael (uncredited) |
| OOscar BlankMan in Church (uncredited) | Man in Church (uncredited) |
| HHazel BoyneScreaming Woman (uncredited) | Screaming Woman (uncredited) |
 Chet BrandenburgMan in Church (uncredited) | Man in Church (uncredited) |
| GGeorge BruggemanSoldier (uncredited) | Soldier (uncredited) |
 Nora BushWoman in Church (uncredited) | Woman in Church (uncredited) |
| TTony ButalaBoy in Final Church (uncredited) | Boy in Final Church (uncredited) |
| MMushy CallahanBurning Soldier at Pit (uncredited) | Burning Soldier at Pit (uncredited) |
| DDick CherneyLooter (uncredited) | Looter (uncredited) |
