[zestyping]

You can do that just with a mirror in the shape of an arrow. Or a mirror with a negative arrow painted on it :)

[makeitdouble]

Yes. It's pretty interesting they went the "projector" way.

I guess there is an issue of the arrow not being lit enough to stand out if the mirror flatly reflects ambient light, it would need to focus a lot more light, which would also make it much bigger.

It might also be that the additional light from the arrow is just beneficial in that specific case.