My styrofoam head(s) haven’t arrived yet but my projector is out and ready to be played with. While hooking up the projector I unintentionally pointed it at a mirror mounted in my office. Turns out projecting on a mirror is a really cool effect!
The only problem I found was that you’re much more likely to get blinded by the projector (duh) looking at it like this. Though it does bounce a nice reflection. I’m thinking that might be useful when it comes time to setup the projector for Halloween. I’d rather not leave it out in the open projecting on the heads. A long mirror opposite the projector might solve this.