A brief clip from the climactic final attack scene later appeared in the 1985 horror film "Fright Night." In that film Roddy McDowall introduces the scene as being from a fictional movie called "Mars Needs Flesh."
The actor who donned the Octaman monster suit could only see through a small pair of holes in the forehead of the monster head. With vision so limited the performers movements had to be very careful as to not damage the suit. This is why the monster moves in such a lumbering way.
The first film for makeup effects legend Rick Baker.
The movie briefly appears in the 1990 movie Gremlins 2 as "Attack of the Octopus People".
The Octaman suit actually does have eight tentacles, two small ones branch off the leg tentacles just above the ankle to complete the octet.