The mane mac bug is they tried to implement acceleration based navigation but failed.  The acceleration part either doesn't refresh completely or switches to rotation partway through the animation.  This makes navigation crosstalk between rotation & translation & studder.

The result is navigating is nearly impossible on a mac.  On Linux, the acceleration is implemented properly, so the crosstalk & studdering doesn't happen.  Ideally, there would be no acceleration on any platform.

On the mac, antialiasing & reflections are much faster than Linux.  Godot drops key release events on Linux, making keyboard input during a slow framerate impossible.  

Reflections from other nodes are horrendous on any platform.  It looks worse than Doom 1.  The only way to get remotely acceptable reflections is to make an environment map of the hangar.  Environment map reflections in godot are acceptable.  No-one has ever made an equirectangular projection from a godot scene.  They  only did it in Blender.  The real BFR may not be shiny at all.