Uh… they probably won't be upside down, depending upon the number of mirrors. However, it still won't work. (1) You attenuate some of the light on each reflection because mirrors aren't perfect. (2) The total length of the virtual tunnel you create will be much longer than the actual length of the enclosure. Your participants will appear to be farther away from one another than they actually are, not right next to one another. (3) Assuming the entire inside is not mirrored (and if it is, it will look weeeeeeird, like a kaleidoscope compound eye view or something), and assuming you could even get the optics right, the view will look like a long tunnel with walls of whatever colour the interior walls of the enclosure look like. So, assuming you use black walls, you should see a long, black tunnel. This is all common sense if you have ever stood between two mirrors. Have a look to see how many iterations of yourself you can see clearly before it gets too dark or too curved (out of alignment, producing a horizon). Even if you have a
meter between yourself and each mirror, that means that each iteration of yourself is two meters apart.