Thanks for the answers and I agree. Variations are not errors. When a casino makes 500 of a strike and no other is known, it's not and error.

If a strike is issued, in quantity, with a spelling error and it's run through the machine without being pulled, or removed and destroyed, it's not an error.

The few, of the many, that you listed are good one examples. That's what makes writing a guide a daunting task. I'd never have known that the copper rings were anything but just another strike if I hadn't been reading here. (but they aren't errors anyway)
Thanks all!

I'm not cleaning this one, risking dammaging it, until I can find out for sure that it's not just tarnished as some have suggested. It's a good possibility that it is just tarnish. But it came from the machine, when the strikes were new, right in the sealed plastic, as made by the factory. That would be an error.

It's gold, and I've seen silver tanish before, it turns black, not gold. Some foreign substance, or mistake at the plant, had to make it change to this bright gold color.