Shortly before TOS-R was released, I ran into a post on another forum about the CGI model having a "tellywhacker" (as that poster put it) on the underside of the saucer. The tiny army tank-like turret and barrel can be seen in this screen cap from the TOS-R "Changeling."
I have never seen such a feature on the TOS Enterprise
prior to the Revision, er, Remastered episodes. That lower cap has always been fully lit (no dark pimple in the middle), and no diagrams have ever shown that—whatever it is. I saw the original model at the National Air And Space Museum around 1979 or 1980. Considering other threads on the reconditioning of that model and the state it was in when NASM first received it, I don't know if such a tiny detail existed on the original.
Does anyone know? After all, one of Kirk's lines in "The Naked Time" is "Now I know why it's called 'she.'" It would be a shock after all this time to learn that the Enterprise
is a stallion.