If you try to send a small companion onto the bridge in Mountain Pass(before the cutscenes is triggered and it gets destroyed by the dragon), it falls through the world. If you try to switch characters, it'll show their camera, but they can't be controlled. Saved games can't be loaded. At this point, the task manager can still be accessed to quit the process. Using the Quit Game button causes the game to get stuck overlaying all windows. Alt+Tab can cycle through open applications, but none, including Task Manager, can be accessed. The PC can be restarted through the Windows menu.