Have you ever had a movie that you were sure was featured on MST3K, but wasn’t? These days everything’s so well documented it’s harder for that to happen, but it’s still possible to get names wrong or misremember what a film actually is.
For me, I was convinced for years that I’d seen Voyage to the Planet of Prehistoric Women on the show. It’s one of those “redub this expensive-looking Soviet film” Corman specials, but they also got Mamie Van Doren and some other women to dress up like mermaids to pad things out. Since they were on Venus, I just assumed it was First Spaceship on Venus. When I finally got around to watching that, I figured I got the name wrong and eventually figured it was Women of the Prehistoric Planet. When that wasn’t it, I again figured I got the name wrong but was still convinced I’d seen it on MST3K. Maybe it was Fire Maidens! Nope. Only when I made a point of looking through the online catalogues did I finally realise I was wrong.
I think what happened in this case is that I saw it about the same time I rediscovered MST3K, watching it in 10 minute chunks on Google Video and YouTube. There were a few non-MST3K movies I watched more or less by accident when they popped up as recommended, and this must have been one of them.