Yes, the Pipeline Hive, or so I think it's called, the floor's leading directly into the hive are slanted, making it impossible to build on it, or even gestate on it. It is possible though to build on the cliffs next to the wall, because they are flat, There are more bugs on this map then only this though. For instance, Fading on the map is just deadly to yourself and a waste of rescources, going into to the Marines spawn is a helluva hard time because you always get stuck in spots when you are blinking out and that can make your game go from fun to failure in a very short time. ^^