The sequence where Alex Rast (Mark Spain) is seen being dangled off the side of a cliff by Gregory Wolfe (Robert Powell) did not use trick photography or deceiving camera angles. Spain was hung over the side of a cliff-face but was wearing a safety-harness which was not visible to the audience as it was attached through the underneath of Powell's white cloak.
The Rast family in this movie are named after members of the House of Romanov, the last imperial dynasty of Russia. The Rast surname is Tsar spelled backwards. Nick Rast (David Hemmings) is named after Tsar Nicholas II (Nikolay II, Nikolay Alexandrovich Romanov). His wife, Sandra Rast (Carmen Duncan), is named after the spouse of Nicholas II, Tsarina Alexandra (Alix of Hesse aka Victoria Alix Helena Louise Beatrice). Their son, Alex Rast (Mark Spain) is named after their heir apparent, Alexei Nikolaevich, Tsarevich of Russia. The names Nick, Sandra and Alex substitute for Nicholas, Alexandra and Alexei respectively.
This movie was filmed in Perth, Australia but both neither the city's nor the country's setting in the film is ever stated. Australia's 'Movie News' magazine stated in an edition published around the time of the film's Australian release that "...the inference is that the story occurs in America. It's said that this has been done intentionally to help boost international sales".
In this film actor Robert Powell underwent six make-up changes whilst playing the Harlequin character.
The opening sequence was inspired by the disappearance of former Australian Prime Minister Harold Holt.