At one point, Lou Ferrigno walked into Menahem Golan's office after reading the original script which was filled with more violence and gratuitous sex and told him that the script was a "piece of shit" and threw into the garbage. Ferrigno wanted a more family oriented fantasy version which is what was finally released against Golan's wishes.
In the documentary Electric Boogaloo: The Wild, Untold Story of Cannon Films (2014), Sybil Danning stated that she would've preferred to have seen another more "adult" version of Hercules. She was probably hinting at the original script that Lou Ferrigno completely objected to and probably the reason that Danning signed on to co-star in the film.
Sybil Danning had a huge crush on her musclebound on-set partner, Lou Ferrigno, although he was not interested in her, romantically (he was married). In her future interviews she would call Ferrigno a "fine specimen of masculinity." Ferrigno was in peak physical condition during the filming.
The movie was supposed to be a star vehicle for Lou Ferrigno - the same "Hercules in New York" (1969) was for Arnold Schwarzenegger. Despite being incredibly successful as a bodybuilder (as Schwarzenegger was), and despite the fact "Hercules" was a bigger box office hit than "Hercules in New York", Ferrigno never became an A-list action hero.
It was Director Luigi Cozzi that wanted a more special effects heavy version of the film. He lamented the fact that the effects didn't come out as smoothly in the final cut of the film as he originally hoped they would because of the films' budget.
Brad Harris played Hercules in The Fury of Hercules (1962). He and Lou Ferrigno worked together in an episode of The Incredible Hulk (1977).
Lou Ferrigno had to have his lines "Dubbed" due to his speech impediment from being deaf.
Filmed back-to-back with I sette magnifici gladiatori (1983) in the Summer of 1982.
The movie was chosen to be part of famous german "SchleFaZ" series. It was aired April 2018 on german TV station Tele5. "SchleFaZ" is a german abbreviation, means "the worst films ever". In that series 2 hosts present the whole film and make fun of it throughout the movie.
Many of the cast were dubbed in post by Marc Smith, Mary Tamm and William Squire among others.