(G-2) - Place a weight on the dais in the lower-right corner of (G-2) to open the two chests. Proceed to (B-3), climb the top of the screen and jump across into (C-3) to land on an invisible platform, Climb up the ladder to appear in (G-2).
(C-4) - From (D-4) jump over the trapdoor (just above the column of head statues) into (C-4). Place a weight on the dais to reveal a coin chest. With careful timing and precise jumping you can jump through the trapdoor in (D-4) and land on the ledge containing the chest in (C-4).
Spring in the Sky (B-9) - Walk through the wall to the left of the ladder in the upper-left corner of the room. Continue left through the passage in (B-9) until you reach the end, then break the wall to reveal the chest.