Interesting. I saw
Flesh Gordon when it first came out in theaters in 1974. It was certainly a hoot and a half, but I don't remember RD's voice being used in it - but then, as most know, I tend to try to forget as much as possible about RD, so the fact that I don't remember him means diddlysquat.
One thing I do remember, though, is that Variety gave it a truly horrendous review, the part of which that still comes to mind is that it was "puerile." Normally that wouldn't be a recommendation, but it made my friends and I want to see it all the more to see if it was really as bad and as 'puerile" as they made it sound. And, of course, the nudity certainly didn't hurt when it came to attracting a bunch of 18-year-olds.