I must be brain dead:
What do I do with the leash? I've been all over the place with all three but can't seem to get rid of the leash. I must be missing something very obvious..
you need the leash to
Spoiler
lift the turtle up tp the tree.
I thing you missed some place that I also found rather accidently:
Spoiler
You can also go behind the building at the left side, right where you start.