I was playing earlier and i went to the top of the far wes building ((With the grapes.)) When I returned to ground level the map remained partly the same. It was odd but not detremintel to gameplay, but i though it should be known, possibly a one time glitch though. Here's a picture of the map after the glitch.
Just the square area it covered remained glitchy after I moved the map added the rest of the detail on the sides but the glitched square remained the same even if I walked back towards the area that was weird.
The corners of the buildings are just the tops of the buildings that you havn't fully explored yet....I think. And that minimap problem is weird. I will have to try it.