1. So the others attacked one night ahead of schedule correct? So wouldn't they be tipped off by the fact that the tents were marked on the wrong day?

2. Is it safe to assume that Alex was born on the island? Why is her mother still alive 16 years later?

3. Why the hell did Charlie trap himself in the room when the grenade was going off? Because he felt it was his destiny? He could have easily got out of that room, and THEN closed the door behind him.