01/08/12 - I'm not sure what hidden items you're missing in particular, but generally, people have trouble with the 4th bottle (obtained by capturing all 10 Big Poes in Hyrule Field, then showing them to the Ghost Shop owner in Castle Town), the Biggoron's Sword (obtained through the infamous "trading sequence" - the first item is a Pocket Cucco that the Cucco Lady in Kakariko Village gives you), the Gold Scale (obtained by catching a 13 lb. or larger fish at the Fishing Pond), and Nayru's Love (obtained from the Great Fairy in the Desert Colossus by bombing a cracked section of the wall on the right side). As for the Gerudo Training Grounds (which the prize for completing is the Ice Arrow), I hope you didn't pick the right (as opposed to left) side in the room with all the locked doors, as it leads to a dead-end. The key you're probably missing is actually found in the "locked door" room itself. On the left side, (after going through the first locked door where the path splits) look up at the ceiling with the Lens of Truth, and the fence-like wall should be extending up into the ceiling. Use the Longshot to grab onto this part of the fence, and climb up, where you'll find a chest with the mysterious "final key" that seems to stump even veteran Zelda players... I hope this helps.