One of the forgotten classics Cold War scifi is First Spaceship on Venus (1959), a Polish/East German production about the first explorers on Venus - who are menaced by a bunch of sentient mud.
It turns out Venus was once home to a thriving, sophisticated civilization that was destroyed by some kind of massive explosion or temperature catastrophe. At least, this is what our intrepid explorers surmise as they are are sequentially menaced by a "radioactive forest" and a giant golf ball that eventually starts glowing red.
Based on a novel by Stanislaw Lem, the movie strains to be educational and serious, with big-budget (and gorgeous) concept design coupled with long, boring scenes full of exposition about space travel. There is literally a five-minute sequence of a guy demonstrating the concept of free fall by floating in the air while his fellow cosmonauts giggle at him.
Though the movie looks remarkably similar to American offerings of the same era, right down to the anachronistically multicultural cast and shiny silver helmets, First Spaceship was a purely communist production. The plot is surprisingly ideology-free, however - this is pure action intercut with the wacky antics of a robot dog creature. It's also one of the few tales committed to film of exploring Venus rather than Mars, which is interesting in itself.
If you love dangerous black goo oozing in reverse, or shiny spacesuits with plush ears, First Spaceship on Venus should be at the top of your DVD queue.
First Spaceship on Venus [via IMDB]