According to Christopher Lee, this film dealing with an uncommon heat wave was actually shot in the middle of winter. The actors not only had to be covered with glycerin to create the illusion of heavy sweat, but also suffered from wearing very light clothes in a freezing season.
Because of the strong sexual implications of the French title, some distributors added several graphic sex scenes in order to exploit that feature in the French adult film circuit. None of the original cast and crew were credited in that version apart from Jane Merrow and Sarah Lawson who were both doubled for the additional scenes.