This. Does your game have a river? If so, humans observing the river will veeery easily be able to spot it's a fake. Because an actual realistic simulation of turbulent river flow is way beyond the largest supercomputers today, and Moore's law has run out of the steam that has made todays consoles have the computing power of your fathers supercomputer.

I'll bet dollars to doughnuts that even twenty years from now, by far the cheapest way of creating a completely photorealistic VR river scene is to build the actual river and record video of it. Then you "only" run into the problem of storing and distributing the petabytes of data you record.