Spoilers below for anyone who hasn't yet watched Legends of Tomorrow's latest episode, and isn't mostly caught up with the other DC shows on The CW.
Tonight's installment of Legends of Tomorrow marked the capper for the most recent DC/CW mega-crossover, and the episode made some big reveals on par with The Flash's high-rated crossover entry. One came near the end, after the new U.S. President (female, but not Lynda Carter) declared metahumans are heroes, when Supergirl revealed she'd spoken to the President about how her Earth has an organization specifically devoted to keeping track of "other" activity. And unless Supergirl was lying, POTUS was into the idea, so we can probably expect to see The CW's other super-dramas better resembling both modern comics and Supergirl in the future, thanks to the Department of Extranormal Operations.
Up until this point in their respective stories, aliens hadn't been introduced into the narratives of Arrow, The Flash or Legends of Tomorrow. Barry clearly had knowledge of them, thanks to his trip to National City last season, but getting both Supergirl and the Dominators was quite a lot for the rest of the heroes to handle. (We assume that the rest of the planet was also freaking out about it, but not a lot of outsider response was visible.) And though we probably shouldn't expect to see extra-planetary visitors dropping by Central City P.D. on a weekly basis or anything, having the DEO up and running would create an easy way to make that happen, not to mention getting more big government influence into Central City.
The DEO was first created by Dan Curtis Johnson and J.H. Williams III for an issue of Batman in 1998, and it was set up basically to monitor anyone that wasn't human, be it superhumans or aliens or whatever's in between. On Supergirl's Earth-38, things are handled by alien J'Onn J'Onzz under the guise of Hank Henshaw, who is currently Cyborg Superman, and the impersonator's alien past has led to this Earth's DEO being more lenient on non-humans.
We obviously can't expect anything remotely similar happening with the formation of Earth-1's Department of Extranormal Operations, as cool as it would be to see actor David Harewood four nights a week. And executive producers for the shows have said that aliens won't play any major roles in the immediate future for the three non-Supergirl series. But again, it's not just about aliens.
Beyond opening up other storyline avenues, introducing the DEO would be a superb chance for the comic book character Mister Bones to join the far-reaching ensemble for his live-action debut, and it's the kind of role that needs the perfect character actor to play him, since his skin, flesh and innards are all transparent. On the page, he's the organization's executive director, and he's worked with the Justice Society on occasion, which is a nice Legends of Tomorrow link-up. As well, fans would no doubt love to see an Earth-1 version of super-agent Cameron Chase, who first appeared in Supergirl last season.
Regardless of who's watching the metahumans - or who's watching the watchers - Legends of Tomorrow will return to The CW next Thursday for its midseason finale, and we won't see the time-traveling heroes again until next year. The Flash and Arrow are also saying temporary goodbyes next week. Head to our midseason premiere schedule to see what you can look forward to when they're all gone.