Assume an item in hands that cannot fit into player inventory. When dropping this item from hands to the ground implicitly, i.e. by equipping something else in hands directly, the item will be placed on the last position where it has been explicitly put on the ground. This hapens only if the last position is considerably far away (say, 300 meters).

Sometimes, items in hand (here: a deer pelt) become invisible while running across an invisible border. Going back over this border makes it reappear.