To their credit trying to copy the 1950s monster movie, the producers went and actually obtained the services of one of the writers of two classic 1950s sf/horror movies Harry Essex. Harry Essex wrote a number of Westerns and film noir thrillers during the 1940s and 50s, as well as an earlier mad scientist film Man-Made Monster (1941) and had made his debut as a director with the Mickey Spillane adaptation I the Jury (1953). But Essex is most famously known as the co-writer of It Came from Outer Space (1953) and The Creature from the Black Lagoon (1954), both of which are formative classics of the 1950s alien invader and monster movie. Although despite an eminent background in the 1950s, one suspects that the success of these films is due to reasons other than Essex It Came from Outer Space was famously rewritten from a detailed treatment by Ray Bradbury, while The Creature from the Black Lagoon is a fairly standard monster movie on a script level but gains all its effect from Jack Arnolds atmospheric direction.
Certainly in his two genre outings as a director, with Octaman and the alien invader film The Cremators (1972), Harry Essex produced two films that have only been remembered by those who laugh at bad films. Indeed in Octaman all that Essex seems to have done is recycle his plot from The Creature from the Black Lagoon scientists go hunting a creature in the South American jungles and rivers where it turns around and starts to hunt them, even develop a lust for the token woman of the expedition. Essex has also thrown in other cliche characters like the huckster carnival showman who has been appropriated from Robert Armstrongs Carl Denham in King Kong (1933). And when it comes down to it, the creature is really interested in nothing other than abducting the heroine which it does not once, but twice.
Octaman was the first screen credit of Rick Baker, later to become one of the top makeup effects artists in Hollywood with the creation of the title beings in King Kong (1976), An American Werewolf in London (1981), Greystoke: The Legend of Tarzan, Lord of the Apes (1984), Harry and the Hendersons (1987) and The Nutty Professor (1996) to name but the most famous of his works. His Octaman creation has an undeniable cheesy effectiveness and is certainly one of the best things about the film. Sadly the film surrounding Rick Bakers creation is all rather tedious. The octaman never really does a whole lot for most of the film excepting stand around in rivers swinging its tentacles. Even when it starts killing people, still nothing much happens.
And then there are parts of the film that are just downright laughable. Like the scene where the heroes manage to surround the creature out in the open air with a circle of flames about 30 feet in diameter and then Kerwin Matthews proclaims: Keep away from him, Steve. The firell burn up all the oxygen around him (as though an open-air fire exists in a vacuum and is not capable of pulling in oxygen from anywhere else around). The most tedious part of the film is where the characters become trapped in a series of caverns while pursing the octaman. These scenes become bogged down in tired cliches about the party running out of air and having to traverse a narrow defile in order to escape, which fail simply because Harry Essex does nothing to make it in any way look like the party happen to be in a series of caves. And then of course there is the biologically absurd notion of an octopus haunting fresh water rivers rather than salt-water oceans where they are usually found.
Harry Essex goes to shoot in Mexico and casts locals as his extras even so though, the film still manages to cast Latin Americans as the equivalent of American Indians, who all speak in pidgin English without using any articles. If Octaman werent so dull, it would really be laughably terrible.