Without seeing your object manager structure and your settings nobody can be sure, but it simply looks like you forgot to toggle the invisible for render state on a object.
Thanks but that is not it. I have double checked to make sure. Oddly the problem has resolved itself. the rendering issue just 'sorted itself', by which I mean it is no longer rendering strangely. I have double checked all the setting in a previusly incremented save, but they are the same. I EVEN made a render save preset of the functioning newer project and applied it to the older malfunctioning one, but the old still rendered crazily, and the new renders just as previewed in the viewport. In both Software and physical renderer.
Is this just a common C4D glitch? If so it's a pretty bad one. I almost missed the deadline.
My main concern now is getting the yellow part of the spline (the beginning) to twist. Rail splines have been suggested. I will try this.