Goofs

The Fire Dragon that attaches itself to the rocket ship Moonlight SY-3 at the end of the film keeps disappearing randomly, at times even within a single scene.

When King Ghidorah approaches the 10 assembled Earth monsters in the film, it changes from a scene showing small-scale puppets to the actual monster suits, and suddenly Minilla appears behind Godzilla.

There are obvious "seams" running down the "sky" in many shots in the film, revealing where the sections of the painted backdrop meet.

In the film, when King Ghidorah fires his gravity beams at Rodan and Mothra, Mothra is knocked into the air by the ensuing explosions, then stops in the air for a moment and suddenly continues flying up again.

From certain angles in the film, you can see that one of the rods supporting King Ghidorah's two wings is detached from the material the wing's skin is made out of.

The holes in the neck of the Anguirus suit used in this film can clearly be seen.

The strings holding up King Ghidorah's three necks can be seen in a couple of shots in the film.

When the news reporter in the film announces that Baragon is destroying Paris, France, it is actually Gorosaurus. The Baragon suit was loaned out to Tsubaraya Productions for use on one of their TV series and was not returned in time for filming.

Even though, chronologically speaking, over 40 years have passed since the previous film, Son of Godzilla (1967), and this film, Godzilla's son Minilla still looks exactly the same as he did before and he still has trouble breathing atomic breath (his atomic breath is in the form of a large ring instead of a beam like his father's). While it can possibly be argued that maybe monsters age slowly, in Son of Godzilla (1967) Minilla grew from a small infant into a much larger early juvenile in a very short time.

When Rodan flies over and destroys two office buildings in the film, there is nothing inside either one of them, only the exterior walls and windows.

If you look closely at the outdoor backdrop , you can see where it looks kind of bubbly showing that it's clearly painted scenery .

In the film, the Kilaaks are said to exist in a temperature of at least 7,000 degrees Fahrenheit, but several humans captured by the Kilaaks from Monsterland are in both Kilaak bases on Earth and the Moon. They should have been incinerated in the intense heat.