The bugs:
1. Shooting at a turret will crash your client
2. NPCs can move through walls
3. When you kill an NPC his body will remain
4. Random buildings exploding as you progress
5. More weird stuff
What can cause this? I would like to point out that it only happens to the players that join and not the server itself.
Don't believe me? Feel free to have a meeting with me on my test server to see it for yourself.