Zoom into the toolkit and take the SNAKE CATCHER (M).
Walk down twice.
Zoom into the tree hole; use the SNAKE CATCHER in it and take the AXE HANDLE (N). The SNAKE CATCHER goes back into inventory.
Zoom into the left cannon; use the SNAKE CATHER in it and take the CHAIN (O).
Return to the Fishing Nets.
Place the AXE HANDLE on the axe head to get the AXE (P).
Return to the Bridge.
Zoom into the tree stump; read the note (Q); use the AXE on the stump and take the BONE (Q1).
Zoom into the dog; give it the BONE (R) and take the DOOR KNOCKER (S).