Many of the extras in the film were unemployed NASA workers.
According to the filmmakers the most expensive item purchased for the film was the suit that Michael Greer wore.
Star Michael Greer was once pulled over by cops who appeared in the film but were unpaid. They then contacted director Willard Huyck and demanded payment for their roles or they would throw Greer into jail. They were paid.
As posted on her blog in 2011, actress Anitra Ford writes: "Shot in 1971, this movie was originally titled 'The Second Coming'. Towards the end of the filming, investors pulled their money out, and the film was never finished. A Frenchman bought the unedited footage, edited it and released the movie under the title of 'Messiah of Evil'. In 2003, in the horror film genre, The British Film Institute hailed 'Messiah of Evil' as 'a rare work of cinematic genius.'"