When you're dealing with multiple shows in a shared universe, what happens on one must impact the others. It's a lesson "The Flash" learned earlier in the season after Barry Allen (Grant Gustin) caused Flashpoint, which left "Arrow's" John Diggle (David Ramsey) with a son instead of a daughter.

Now it seems the Legends of Tomorrow are the latest culprit -- but the changes they've made are on a much grander scale than anything even Barry could dream up. In their battle against the Legion of Doom, reality itself has been massively altered. When that happened, the world became a much more miserable place, with many of our favorite heroes - from The Flash to Black Canary -- dead.

What does this do for the other shows in the shared "Arrow"-verse, though? From what we've seen so far, absolutely nothing. "Legends" is sort of playing in its own sandbox on this one and while, in theory, what happens there stretches across all of the CW superhero shows, chances are you're not going to be seeing changes elsewhere.

Granted, by the time "Legends of Tomorrow" wraps up its second season after the next episode, things should be returned to normal. Still, all of that said, "The Flash" has done a lot of hand-holding with Barry in Season 3, explaining how changing the timeline can screw everything up. Can "Legends" actually return things to exactly as they were before the Spear of Destiny got involved, or will we see small changes pop up here and there throughout the "Arrow"-verse?

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After all, it's not like all of the changes made were bad, right? We got to see "Arrow's" Felicity Smoak (Emily Bett Rickards) suited up as a masked vigilante, taking the fight to the Legion of Doom. That particular confrontation did not end well for her at all, but perhaps a little of that fighting spirit will stick with Felicity in future seasons of "Arrow." While she's a major player in the team, it's rare that she's in the field. It's easy to see she's got the moves when it comes to fighting, so perhaps a little training is in order to get her ready for the street.

Whatever happens, "Legends" needs to be careful with how it treats time. The beauty of these shows existing in the same universe is how they all work together. But that can also be the drawback: If they work together, they have to work the same. The rules apply across the board -- and that leaves us wondering  what exactly the "Arrow"-verse will look like, once "Legends of Tomorrow" is done with it.

The "Legends of Tomorrow" Season 2 finale airs Tuesday at 8 p.m. ET/PT on The CW.

Posted by:Chris E. Hayner

Chris E. Hayner is equal parts nerd, crazy person and coffee. He watches too much TV, knows more about pro wrestling than you do and remembers every single show from the TGIF lineup. You may have seen him as a pro-shark protester in "Sharknado 3." His eventual memoir will be called "You're Wrong, Here's Why..." TV words to live by: "I'm a firm believer that sometimes it's right to do the wrong thing."