Apparently after you've taken it to the end, the puzzles change a little. I went back to try to help with the sign and barely got past the blinking eyeball on the tree.
On the sign, there are at least four changes in the wording of the sign. The other is the rivet in the top center.
Bridge with walk/don't walk: missing rock at bottom, missing point on top of sign, missing slat on bridge, missing grass on left side of bridge, missing cattail bottom right.