Locate all the puzzle pieces which can be found in the following locations. They will have a transparent appearance and will disappear after a brief time. You can force them to reappear by exiting and reopening the game, then flying along the ground until you find it.

Above the pond.
Partway up the hill that leads to the cliff.
The bottom of the hill, after a tree.
The top right of the gate.
The top right of the second tree.