Trailer
 | Tim Considine as Frank Hardy |
 | Tommy Kirk as Joe Hardy |
 | Florenz Ames as Silas Applegate |
 | Russ Conway as Fenton Hardy |
 | Sarah Selby as Aunt Gertrude |
 | Robert Foulk as Jackley the Plumber |
| Carole Ann Campbell as Iola Morton |
| Donald MacDonald as Perry Robinson |
 | Arthur Shields as Boles - Ex-Gardener |
 | Charles Cane as Police Sergeant |
 | Frances Morris as Landlady |
| Brick Sullivan as Policeman |
 | Mort Mills as policeman |
 | Don C. Harvey as Policeman |
 | Dan Sturkie as Police Detective |
 | William Henry as Policeman |
| Jess Kirkpatrick as Policeman |
| Directing | |
| Charles F. Haas | Director |
Sound | |
| Robert O. Cook | Sound |
Directing | |
| Edle Bakke | Script Supervisor |
Writing | |
| Jackson Gillis | Teleplay |
Crew | |
| Gordon Avil | Cinematography |
Production | |
| Russ Haverick | Production Manager |
Sound | |
| Dean Thomas | Sound Mixer |
Editing | |
| George Jay Nicholson | Editor |
Art | |
| Bruce Bushman | Art Direction |
Costume & Make-Up | |
| Lois Murray | Hairstylist |
Production | |
| Louis Debney | Production Assistant |
Editing | |
| Joseph Dietrick | Editor |
Art | |
| Fred M. MacLean | Set Designer |
Editing | |
| Al Teeter | Editor |
Costume & Make-Up | |
| David Newell | Makeup Supervisor |
| Carl Walker | Wardrobe Supervisor |
Sound | |
| William Lava | Music |
Costume & Make-Up | |
| Chuck Keehne | Costume Designer |
Directing | |
| Robert G. Shannon | Assistant Director |
Art | |
| Marvin Aubrey Davis | Art Direction |
Crew | |
| Walter Castle | Cinematography |
Visual Effects | |
| Ub Iwerks | Visual Effects |
Sound | |
| Thurl Ravenscroft | Theme Song Performance |
Writing | |
| Edward Stratemeyer | Novel |
