@Nescio (In case I forgot something)
This is intended, those overlays are over the ground to prevent something called z-fighting flickering. Flickering occurs when two planes here the select ring and the ground are too close to each other. To prevent that everything is raised by a small offset. It's the same for building except you don't see the selection ring when not selected.
I guess you could hide them for the screenshots, but that would require some XML edition?