Okay, the felony thing was hyperbole, and the "all employees" is only accurate from a certain point of view (that equal employmeant practices do not apply to communists).
The law, to my knowledge, has never been used, and it is a little confusing because it's scattered across multiple sections.
The governing section is here:
NRS 613.360 Actions permitted against member of Communist Party or related organization. As used in NRS 613.310 to 613.435, inclusive, the phrase “unlawful employment practice” does not include any action or measure taken by an employer, labor organization, joint labor-management committee or employment agency with respect to an individual who is a member of the Communist Party of the United States or of any other organization required to register as a Communist-action or Communist-front organization by final order of the Subversive Activities Control Board pursuant to the Subversive Activities Control Act of 1950. (Added to NRS by 1965, 693)
Is there still a subversive activities control board?
The specific law about schoolteachers may have been changed since I last looked at it in the 90s. Apparently the only thing specific to teachers now is that we're not allowed to teach communism with the intent of indoctrination. Or it might be in another location, or I might just be remembering things wrong. It could also be in the NAC (as opposed to the NRS). I don't work in the DA's office anymore, so I don't have access to Westlaw :( Between Westlaw and the Oxford English Dictionary, I was in nerd heaven!
I do know that when you take the Nevada School Law test and when you take the school law class, the admonishment that teachers aren't allowed to be registered communists is very clear. I have an old textbook around here somewhere...
Look around for yourself, if you're interested.
http://www.leg.state.nv.us/law1.cfm