Battle in Outer Space

Developed as a story proposal in 1957 by Jojiro Okami, the film underwent four script drafts by Shinichi Sekizawa. Though the characters of Dr. Adachi. Dr. Immerman, and Etsuko (the same names of characters that appear prominently in The Mysterians exist in the finished film, it is believed in the first draft they were to be the exact same characters as those from The Mysterians carried over. This element was likely present in the story pitch by Jojiro Okami, who had gotten the ball rolling with The Mysterians as well. Apparently, the final script just kept the names and they are not meant to be the same characters.

In the second draft of the screenplay, instead of the aliens controlling Dr. Achmed, shadowy alien specters infiltrate the space center and spy on the conference. In one scene, Etsuko is working in her office and is startled by the appearance of a specter-like alien spy. When the alien leaves the room, her paperwork flies all over the place. In another scene, Katsumiya spots what appears a small tree outside his quarters, but is in fact another alien spy. One of the alien spies was to appear before the conference meeting. These ideas were scrapped because they would have required several optical effects; it was decided that the aliens would use mind control on humans to do their dirty work.

In one of the original scripts, there were scenes where the crew-members ate their meals in a cafeteria on the rocket ship. In the battle with the space torpedoes, the plates and food were to be tossed all over.

Storyboards for an unused scene had the human astronauts spot a flying saucer go through a tunnel, leading them to the alien base.

Originally the Natarl attack the Earth's forces with their own land based vehicles on the Moon. These vehicles, which reassembled yellow pill bugs with antennas, did not make it into the final version, and instead the Natarl flying saucers appear during this sequence to attack. Originally in one of the early drafts, the Panama Canal and Venice were to be destroyed in a fairly major effects scene, but it was decided to save money by using paintings. Early designs for the Natarl aliens were insectoid, as they had six tentacle-like arms and only one eye.

In an early version of the story illustrated in the storyboards is a more interesting version of the encounter with the Natarl base. Instead of the astronauts keeping their distance and avoiding direct contact with the aliens, Katsumiya takes a strike team inside the Natarl base and succeeds destroying it from within. However, the imagery was totally reminiscent of the alien base from The Mysterians (1957).and building extra sets would have been too costly and repetitive.

In an earlier draft of the script, the Natarl Mothership's anti-gravity beam was used to destroy the Eiffel Tower in Paris, the Kremlin in Moscow, and the Golden Gate Bridge. But in the end the anti-gravity beam is used for Tokyo. In the original scenario, a signal Natarl flying saucer destroyed Tokyo with the anti-gravity ray instead of the mothership. The original plan was that the alien mothership would never approach the Earth, but this was changed by Eiji Tsuburaya during shooting.

The exterior shots for the Space Research Center was the National Sports Center built for the Tokyo Olympiad in 1964. Interior shots were shot on sets back at Toho.

The slow motion, gravity-stricken walk of the cast on the Moon was an idea from actor Yoshio Tsuchiya. Actor Ryo Ikebe uncharacteristically protested, declaring it was "just a movie" at the idea of the slow-motion walk. However, Ishiro Honda ended up siding with Tsuchiya. The incident did not sour Ikebe, though, who worked again with Honda a few years later on Gorath (1962).

When Apollo 11 landed on the Moon on July 20, 1969, ten years after this film was released, Eiji Tsuburaya watched the “Great Leap for Mankind” on live television. Shortly afterwords, he later told Sadamasa Arikawa, “We were right, our special effects team did a great job. Now, we can hold our heads before the public.”

The beginning of the film shows see three flying saucers traveling though space while the credits roll across the screen. These scenes were taken with the camera platform and the saucers attached to an overhead rail that move them both along at the same speed past the outer space backdrop.

The tunnel in the ray gun test chamber was achieved by using a backdrop painting done in forced prospective making it look like an endless tunnel.

To film the two SPIP rocketships flying up into the sky, the two six-foot miniatures were radio-controlled and launched from under a bridge suspended 100 feet (30 meters) above the ground at Miura Point, connecting the cities of Miura City and Joyga-shima.

For the miniature wire-work, it was the job of Fumio Nakashiro, who used thin piano wires ranging from 0.1, 0.2 and 0.25 millimeters. They were painted to blend in with the background of outer space, but when they could be seen when it was a sky background. Sometimes you can see the wires shimmering in the light.

The air jets effects for the Moon rovers was created using a water spray.

To simulate buildings being torn and thrown up into the air, miniatures were mostly made of lightweight materials such as cardboard, wafer-thin paraffin, gypsum and Styrofoam which was pre-cut and assembled. Some pieces were trained on the miniature set, blowing everything upwards thanks to multiple compressed air tanks underneath the set. The soldiers falling upward was achieved with a camera moving over the actors, and then superimposing them over the miniature action via a traveling matte.