I have my homebase on a planet and I dock all my ships to it. From time to time I log on to find a ship stuck in the planet core. I then have to ask an admin to either teleport or destroy the ship.
It has happened many times. Today I logged in and found some 5 of my turrets stuck there. It looks random enough, as some turrets are still docked to the ship (and the ship is in turn still docked to the base). A couple of them are turret bases only that kept attached to the ship while the barrel is stuck in the core...
May be related to: http://phab.starma.de/T67