I love this movie, but every time I watch it, I discover more and more problems with the plot. Sure the headache inducing time travel angle causes a lot of problems, like why did the Futurians need to travel back to 1992 at all? Why not just go straight to 1944 directly and remove the Godzillasaurus themselves? And why does Ghidorah wait until 1992 to attack when it was created in 1944? Also, the rest of the Heisei series follows the timeline of Return of Godzilla and Godzilla vs. Biollante even though those should have been erased from history, according to this movie.
But something else occurred to me when watching this recently. Yet another thing that doesn't make any sense. Isn't it stated that the Godzillasaurus that was mutated by radiation during the war in 1944 became the Godzilla that destroyed Tokyo in 1954? The one that was killed by the oxygen destroyer?
So then how would removing it from the timeline before it was mutated prevent this current Godzilla (which is a different creature that was first introduced in 1984) from existing? Unless they're saying that the Godzilla from this series in the same monster from the original 1954 film.
I know that the Heisei Godzilla ended up being created anyway due to a submarine crash but the question still remains about the two different Godzillas in this continuity. He can wiping one from existence prevent the other? Can someone please elaborate on this?