No N-numbers (equal to vehicle license plates) on the Janet planes... unmarked as was said. No N-numbers and if you ask passengers they won't tell you where they're going or where they were... that's if you can even get near a Janet passenger. The Janet parking lot and terminal area is well guarded compared to any normally protected airport in America. Good ol' Area 51 - one of the United States' most secretive places.
A good link for people interested: www.dreamlandresort.com
http://maps.google.com/maps?t=k&hl=en&ll=36.091551,-115.16508&spn=0.001261,0.002004&om=1
Full details on the fleet here:
http://www.lazygranch.com/janet_registration.htm