Oh, and I thought I should say, there is evidence remaining in the film of the original ending.
1: When Littlefoot sees his mother's ghost, look below him. The lake that they bathed in is there, and above it is the plateau that they pushed the big rock off. Except, the rock is still there, waiting to be pushed off. Also, when he scrambles after her, the rocks on the hill resemble the ones on the hill he climbed after leaving Cera.
2: When bathing in the pond, they hear Sharptooth's roar. Look at where he is standing; the air to the right is green, as opposed to the brown everywhere else. Also, there are plants growing on the hills to the right.
Seeing this, I wonder if the cave that Sharptooth went into was the same one Littlefoot ran through, chasing his mother's spirit.