Bad movies start with bad writing. A screenplay by Ed Wood, Jr. titled "Venus Flytrap" was filmed in 1967 and not released until 1970. It was an American-Japanese coproduction with much of it filmed near Tokyo. I came across it after following Tsarstepan's thread on RiffTrax.
It was re-titled "The Revenge of Doctor X" by mistake because it was released together with a horror film from the Phillipines. The distributors erroneously used credits from the wrong film.
In addition to maneating plants, the movie throws in volcanos, a hunchback dwarf, and topless female pearl divers.