The controllable turret you get from a milestone in Zombie Massacre is broken. The barrels have been disconnected and seems to be centered in the condo. All the shooting is broken because of this as the rays and sounds effects originates from the barrels.
Here you can see the turret barrels being disconnected.
Here are the barrels.
Here you can see the weird shooting. As you can see, it goes from the barrels to where I’m aiming.
Another problem I found with it is that if you keep shotting and then press the AltGr button that is present on some keyboards, you will leave the turret but it will keep shooting. At least in my case on my Swedish keyboard.