It took me years and years to track down a copy of this strange comedy.
I first heard about it in the early 80s, when Peter Lawford's widow, Patricia Seaton, was interviewed and asked to comment on Lawford's final film. I remember her saying that Orson Welles did not socialize with the cast, and he actually had his meals brought to him so he could eat privately.
This interview was about 1983 (after the film was completed) and then I believe that years later, the movie eventually premiered at the Cannes Film Festival, and then was never released theatrically or on tape thereafter. Today, it seems lost and forgotten, despite the all-star cast.
Tony Curtis seems to be having fun with this role, but other than Mr. Curtis, the other stars show up rather briefly.
Also, actress Marisa Berenson has a role, but she is not listed in the IMDb credits, nor is Parsifal listed in her own filmography.
One of the oddest devices in this comedy is how the director likes to speed-up the action for comic effect, reminiscent of older, zany screwball comedies.
I appreciate the interesting insight from the other user commentators, who provided the information that this personal "vanity" project is based on the eccentric life of the Salkinds, the producers of the Superman and Three Musketeer films, among others. That helps shed some light on this movie, but doesn't make it a better viewing experience, unfortunately.