20 Awesome DC TV Easter Eggs You Probably Missed
2. Crisis On Infinite Earths (The Flash)
That newspaper clipping Harrison Wells had from the future teased a lot more than just the Wayne Tech/Queen Inc. merger. With the headline 'Flash Missing, Vanishes In Crisis' and another story 'Red Skies Vanish', they're referencing a pretty major comic book event. Crisis on Infinite Earths was a big DC crossover series, used to streamline their decades-long continuity, and featured multiple versions of every major character.
During that story, Barry Allen dies to help save the world, hence Flash vanishing in a crisis. Another nod can be found in the season finale - and indeed Season 2 opener - when the singularity opens up above Central City, bearing a resemblance to events in Zero Hour: A Crisis in Time, one of the follow-ups to Crisis on Infinite Earths.