Valentino
That's a short - it doesn't count. And, IMHO, it is quality entertainment. But I admit I am laughing hysterically right now as I had not thought about this film in many years. Truly a classic.
And yes, Robot Monster is indeed the mystery film. A small family group are the last remaining people on earth who try to avoid being killed by the guy in the gorilla suit and diving helmet. Every once in a while, for no apparent reason that has any relation to the plot, the movie cuts to old cheesy stock footage of iguanas and other lizards with cheap fins and horns glued on, playing the parts of fighting dinosaurs. Really bad.
Bill, tgo