The Arrowverse has grown far larger than perhaps anyone would have expected. There are countless easter eggs to look out for throughout their various shows, but not all of them actually get paid off. In regards to the larger Multiverse
, many of these major items, settings, and characters have come into play; in the Arrowverse they have yet to make a full appearance though.
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Was Comic-Accurate (& 5 Ways Warren Christie
It's not always clear as to why an easter egg is forgotten about. It could be that plans have changed, or it was only ever meant to be a fun nod for fans of the comics books. Regardless, there's clearly a lot more canon mythology to explore in the CW's version of the DC Universe