story identification - Movie from 70's or earlier about a genetically created organism that almost took over an island

It was an older movie I watched on TV in the US, probably around mid-80s, but the movie was obviously much older. It had the same cinematic feel as Invasion of the Body Snatchers. I'm pretty sure it was a legit movie and not a "made for TV" movie.

A creature was created in a lab (I think by accident). It was shaped like a fried egg (mostly flat with a hump in the middle). And I'm 75% sure it also had a single eye stalk; think the trash compactor monster from Star Wars: A New Hope.

Only one was created but it reproduced by splitting. I recall a scene where one was cut in half by an axe, but just became two monsters.

The part I remember for sure is at the end, they managed to stop/kill all the monsters, and the hero stated something to the effect of, "Thank goodness this happened on this isolated island. I couldn't imagine what would happen if this happened on the mainland." The scene then fades to a stock image of a laboratory, and you hear someone talking in Japanese (not English with an accent, but the actual language). They seemed to be talking excitedly, and then the screaming starts, I'm sure to imply that these scientists created the same thing, but now in a major metropolitan area.

Answer

Could this be 1966's Island of Terror starring Peter Cushing? Here's a clip on YouTube which has a creature being attacked with an axe before splitting into two creatures. The axe attack starts at about 1:15 in the video.

The creatures are called "silicates" in the film and look very much as you described. Your plot description also matches pretty close to Wikipedia's plot summary.

You said:

A creature was created in a lab (I think by accident).

Wikipedia confirms this:

...in his quest to cure cancer, Phillips may have accidentally created a new lifeform from the silicon atom.

You also said

...the hero stated something to the effect of, "Thank goodness this happened on this isolated island. I couldn't imagine what would happen if this happened on the mainland."

Wikipedia:

...West commenting on how fortunate they were that this outbreak was confined to an island. Had it happened on the mainland, he notes, they might never have stopped them in time.

You again:

The scene then fades to a stock image of a laboratory, and you hear someone talking in Japanese [...] They seemed to be talking excitedly, and then the screaming starts

Wikipedia again:

This sets up an epilogue and a visit to the satellite program, in Japan, where the techs are duplicating Phillips' work – with the inevitable result. A technician walks down a corridor, hears a strange noise and investigates before screaming.