Art director John St John Earl's final film and the only time he is credited for special effects.
The monocellular creatures are reminiscent of those in Caltiki, the Immortal Monster (1959), which also features a scene in which one of the characters loses a hand.
In the French version (post-synchronized) Edward Judd is dubbed by Jean-Claude Michel / Visa d'exploitation en France : #38125
Italian censorship visa # 62966 delivered on 29 August 1973.
The car in which Cushing, Judd and their passengers tour the island is a 1948 Austin Sixteen.