Twiggy from Buck Rogers cameo
I don't know if this has been posted or not, but I've heard about a R2D2 cameo so I thought I would share another possible cameo. Right after Kirk, Spock, and the cadets are dismissed to board the shuttles and go to Vulcan, take a look at the first line of cadets that are marching in. One of them looks just like twiggy from Buck Rogers. Its a quick scene, but It could be another tribute to other Sci Fi shows.