Nevermind, found a couple more bugs. Near the shadow of the balloon, hold down-left by the tree to walk up the rocks and out of bounds. You are still limited by the terrain steepness, and it can be hard to see where you are vertically as you don't cast shadows onto the rocks, a bug in of itself. I don't think it is possible to get past the wall by the waterfall, although placing a movable stone near the left tree, and climbing up the tree onto it looks close.
Finally, picking up a stone at a different y elevation to normal (easily achieved with the out of bounds glitch above) has the stone hover in the air at that height relative to you. You can also pick the stone up facing away from it, and it will follow you behind it. Placing the stone down leaves it hovering in the air.
These bugs were also gound in the web build.