The singularity may have been closed, but there is still a breach somewhere in Central City, allowing Zoom to send metahumans through from his world into this one. Professor Stein spends much of the episode searching for the breach, and at the end has come up with a couple of startling results. The first is that the biggest of these is actually at STAR Labs, meaning they're sitting right on top of a portal to another world. As if that wasn't enough, it's not the only one, and there are in fact 52 different breaches around Central City (the number being a nice nod to the comics). That means there are potentially 52 worlds that could be explored on the show, 52 different versions of characters, and an almost endless amount of storylines they could use involving these. And it's only Season 2. How many of the worlds will we actually get to visit, not only this year but in the many that are surely ahead?