I noticed that when people build something really far above or below the map, you start seeing bricks that are being built on the map.
This happened on [IRK] clan server.
KITTY was building giant stairs, and once they went high enough we started seeing bricks being built out of no where in mid air, we could also walk through those bricks so it's like they were never there.
Once I Self Deleted I saw those builds in the bedroom.
Also, I might be wrong, but I think it only does this with macros, both "illusion" bricks we saw were macros people made and we saw them up high, no non-macroed bricks were appearing.
I'm guessing this is because we went over the sky-box, but than why do only macroed bricks appear?