The CRTs utilize RenderTextures to render text on the screens (RenderTexture.active=thing; GUI.Label(stuff); RenderTexture.active=original, basically), and I'm not sure how Unity's Linux support would react. I'll see if I can figure something out, maybe try using a different version of Unity 5 to build.
Interestingly, this isn't the first weird graphics-related bug I've gotten; the Mac version outright seems to not render *anything*, just being a grey-blue screen on launch. I've not done any bugfixing on this since Ludum Dare. I'll work on it...eventually. :P