Vera Fusek
President of EarthPeter Birrel
Draconian PrinceLawrence Davidson
Draconian First Secretary (uncredited)Timothy Craven
Cell guard (uncredited)Barry Ashton
KempJohn Rees
HardyRoy Pattison
Draconian space pilotKarol Hagar
SecretaryDennis Bowen
Prison GovernorRichard Shaw
CrossCaroline Hunt
TechnicianBill Wilde
Draconian captainIan Frost
Draconian messengerClifford Elkin
Earth cruiser captainMichael Kilgarriff
Second OgronRick Lester
Third OgronRamsay Williams
Congressman BrookStanley Price
PilotLaurence Harrington
Lunar guard