Ηθοποιοί επεισοδίου
Jon PertweeThe Doctor
Nicholas CourtneyThe Brigadier
Caroline JohnLiz Shaw
John LeveneSergeant Benton
Ronald AllenRalph Cornish
Michael WisherJohn Wakefield
William DysartReegan
★
Steve PetersAstronaut
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Neville SimonsAstronaut
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Ric FelgateAstronaut
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Joanna RossControl Room Assistant
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Peter Noel CookAlien Space Captain
Geoffrey BeeversPrivate Johnson
Peter HallidayAliens (voice)