I'm not sure what you're referring to. There is no node called BGCOLOR. There is a node labelled "BG COLOR" buried in the "Background" material but this will not have anything to do with reflections or mirrors so don't go there.

There is an input to the Reflect node called "Background" but you would only use that if your world is empty. Your world should not be empty because you should be using my environment sphere to provide the missing "rest of the world".

Note: If you have exactly one material and no intention to change the environmental image, and don't intend to do realistic blurred reflection, then yes you can use Sphere_Map and attach to Reflect's Background input. However, you will have no ability to make a blurred reflection. If you want a different environment you'll have to change it in many places instead of one place, etc. There are tons of reasons not to do what you sound like you're trying to do.

A mirror material is utterly simple. But - not at all achievable in the "simple" view of the material room. Go advanced.

http://www.renderosity.com/mod/forumpro/?thread_id=2772892&#msg3463314

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)