What Dr. Adachi Said.

At the end of the Japanese language English subtitled version of the Mysterians Dr, Adachi saw a few Mysterian flying saucers flying away, and said that the Mysterians were doomed to wander the universe forever without a home.

Dr. Adachi seemed to forget that the Mysterian invasion force should have been just a small proportion of their total population. The Mysterians said that 80 percent of their children were born deformed, which implies there was a population of female Mysterians,and none were seen on Earth.

He also seemed to forget about the Mysterian space station obiting the Earth, and about the hypotheticla moon base Mysterian saucers were photographed coming from, and the planet Mars, where the Mysterians claimed to have lived for 100,000 years.

Thus it should have been possible for the Mysterians to invade Earth again later.

And Battle in Outer Space (1959), made a few years later have have originally been planned to feature a second Mysterian invasion, even though in the end the invaders came from the planet Natal.