A shadow is caused by the absence of light, at least enough light to cause a noticeable difference where the shadow is seen. To have a shadow in a dark room where nothing of substance is casting a shadow would imply that the shadow area absorbs more light than its surroundings. If this shadow moves around then possibly something more than light play is going on. Outdoors would be a tricky situation esp. with a rising moon coming up in the background.
A trail goes two ways and looks different in each direction - There is no such thing as a timid woodland creature - Whatever does not kill you leaves you a survivor - Jesus is NOT a bad word - MSB