Two different houses were used for the Zaroff estate: One for exteriors and a second one for interiors.
An unrated X-rated version was also released under the title Sexy Nature. It includes 25 more minutes of footage than the original film, including director Jesus Franco's longtime companion and wife Lina Romay, who was an unabashed exhibitionist, having hardcore sex in front of her husband and the male crew.
The film is essentially a reworking of The Most Dangerous Game (1932), except the original had a Count Zaroff, but no Countess.