Towards the end when Archer cries out loudly "Noooooo !!!" in the forest, birds are seen flying from the trees. It was in the dead of winter; all birds would have flown south so none would be nesting in the trees.
It is a common misconception that all birds fly south for the winter. In fact, about a quarter of birds do not; these include northern cardinals, blue jays, chickadees, black birds, sparrows, nuthatches, and woodpeckers.