Made an account just to post this since it's been driving me insane:

http://i.imgur.com/OqmUdMP.jpg
The windowsills here clip, I don't know if it's intentional or not but it makes rocket jumping using that wall nearly impossible because you just hit your head unless you go nearly flat. There's nowhere to jump to using them so I think they're essentially useless.

http://i.imgur.com/baM55TL.jpg
If you aim about where I am, you can shoot through the fence here. I know it's on blu side, I didn't check red. This is at the bottom of cliff by the health pack.