The blank in the equipment side is the magic key, it wasn't needed when I made the game.

The green crystal is found in the first island, you'll need to burn a bush next to a tree on the screen below the 2 graves. I recommend burning it from the bottom or the top, not the side, as you'll have to use the whistle to get unstuck.

The bait has been used all game, it was the registration form.

Lens of Truth is a bonus item for the low, low price of max rupies (999).

There are only 4 heart containers found on the mountain. The rest (HCPs) are found in the 2 overworlds. 18 in the first, and 18 in the second. I believe I hid them pretty well.

If you want the best chance of finding them, seek the Lens of Truth in the mountain overworld, and use it to find them.

You are also missing the gold arrow, but that comes almost at the end.