The ears and wings are hidden by default. To make them appear or disappear, you simply left-click on their location. This can be tricky (due to overlying clothing and other SDT layers) so the recommended approach is to press Tab until a highlight bracket appears in the desired position, and then press Spacebar to make the item appear or disappear. Left-clicking anywhere else (e.g. background) will make the highlight bracket go away.
The ears and wings are animated. This is not a physics-based effect and does not require the Loader. Both animations are hand-drawn loops.