>Some physicists are questioning if General Relativity is totally accurate.

No physicist has ever thought that GR is totally accurate, not even Einstein. We've known from the very beginning that GR and QM are incomplete.

>The simulation has limits so the extreme edges "break" the rules.

What rules does it break? The universe is under no obligation to obey human intuition.

>It is possible the universe is the same way...

That's absolutely nothing to suggest that it is. We humans evolved to have an intuitive understanding of the world we interact with; therefore, we should expect physics to diverge from our evolved intuition when we go beyond humans scales - namely, the very small, very large, very vast, very hot, very rarefied, etc. Go beyond STP and scales of metres and seconds, and we should expect to hit counterintuitive results.

It would be more indicative of a contrived simulation if we didn't encounter edge weirdness.