[yetihehe]

How to detect imperfect simulation: some unexplainable missing wavelength bands, or quantisation of results where it should be continuous would hint at "cutting corners" in simulation, like steps in energy levels from very distant xray sources perhaps?

As far as we know, our "physics" does not show any possible imperfections, or we didn't thought of all imperfections which could arise in simulation.

[__MatrixMan__]

I think you're setting the bar far too low. An inability to explain why certain frequencies produce no EM radiation would be unsettling, but maybe reality is unsettling. It would not be enough to jump to the conclusion that nothing we've ever measured is actually real.