Your railing is causing rendering errors. Or, something else is.... kind of hard to tell from just that one shot. It also looks like your texture is missing. If you are using a shader, I believe I'd check the spelling.
On the railing: you have too many surfaces pressing up against a single surface. This is common when making ladders and railings. Cut the longer brushes into smaller sections.
... ive had this problem before and it has been on a surface of a grassy area surrounded by a fence type thing so i beleive your railing is causing it... just adding on to evidence to support everyone else who saids thew railing lol... oh and what skin are you using for your OS? that looks cool.
yes, where? i was ging to ask that but you stole it from me! Also i will be adding to that evidece, either divide the platform into two/3/4 pices to lower the amount of brushes touching the plat...
