The altitude thing...
Many people reported seeing the plane extremely low in that area:
http://www.ibtimes.co.uk/missing-mal...to-sea-1439730
If it were indeed that low, they passed quite a few airports where they could have potentially landed. (I don't knwo if each runway was capable of receiving a 777 though, and who knows if they were lit up at that time of night)
Large map or airports in the area: