20 Million Miles to Earth (1957)

Oh… the ACTING. Ugh…the dialogue! Secret expedition returns from Venus with a live specimen that grows rapidly and begins terrorizing Italy. See -- they've got to capture it alive because if they don't figure out how it works, humans will never be able to breathe the atmosphere on Venus. No one ever asks the obvious "why do humans need to breathe on Venus" question, though. Too bad 'cause it could've saved a lot of time. Just a monster movie padded with ridiculous science talk and a wholly unbelievable romance. Skip it.

D+