Probably a common question but hey...
 

With the cliffhanger of Alien Rangers/resolution in Zeo... didn't Goldar take the Zeo crystal in the cliffhanger? If so, why was it in the rubble of the Command Center?

The Zeo Crystal erased their memories of their evil lives. In the confusion they must have dropped the crystal.

That explains that strange Goldar-Rito slave story... man, that was terrible.

They lost their memories and drop it because they didn't know what they had it for.

Re: Probably a common question but hey...
 

I don't think it was just a case of the Zeo Crystal erasing their memories but more like reacting to what it likely heard Rita said. We don't know how far it can hear since it can obviously react to spoken words. It wasn't fully united at the time since I think it was still missing Aisha's Sub-Crystal but just because it wasn't fully united doesn't mean it didn't register what was being said around it in the process.