[quote="Simbaholic"]I would expect Mufasa's last thoughts to be, disbelief, as shown by his expression as soon as Scar digs his claws into him, I would imagine him to be thinking "What are you doing!?" because as his brother he would expect him to help. Then when Scar says 'Long Live The King' from his horrified expression, I would believe he knows he is about to die.
As for Simba, I just looked at the scene again again, and from what I can see there seems to be a rock stack/formation blocking his view of Scar and Mufasa, and can only see when Mufasa is falling down.
And about being thrown off, pretty much what KM said, body size and gravity play the part

[/quote] I agree