This is something that completely blew my mind. Last week I was playing randomly with a mirror and my pen and then I noticed that the image of the pen was also having its shadow on a nearby wall.
How is that even possible? For something to form a shadow it must physically block the path of light but a virtual image is "virtual". So how can it block the path of light?
Here's a picture of that:
To add :- There is only one light bulb in the room.