Tonight's episode of "The Flash" was absolutely incredible! It paid homage to so many DC Comics characters, it pulled no punches in surprising Team Flash with their doppelgangers, and it brought an intense emotional depth that viewers have come to know and love from this show. "Welcome to Earth-2" might be the strongest episode of the entire series, and considering it's a two-part episode, next week's episode, "Escape from Earth-2" might be even better!

The episode kicked off with Team Flash closing all 52 Earth-2 portals except one -- the one inside S.T.A.R. Labs. They left this breach open so that Harry Wells (Tom Cavanagh,) Barry Allen (Grant Gustin,) and Cisco Ramon (Carlos Valdes,) could travel through it to Earth-2 to save Harry's daughter, Jesse Quick (Violett Beane.) While half of Team Flash made the trip to Earth-2, Caitlin Snow (Danielle Panabaker,) Jay Garrick (Teddy Sears,) and Detective Joe West (Jesse L. Martin,) were left on Earth-1 to keep an eye on S.T.A.R. Labs and Central City. While they were alone on Earth-1 a metahuman named Adam Fells/Geomancer (Adam Stafford) attacked the city looking for The Flash. Jay Garrick had to use some of the new Velocity serum, which Caitlin named Velocity-7, to help Joe stop Geomancer. Jay was reluctant to take the Velocity serum because it was the real cause of his illness and his loss of speed, but Caitlin engineered a version she considered safe for temporary use. Unfortunately the serum wore off, and Jay was almost killed. The other problem Jay and Caitlin faced while the team was gone was fixing the breach, because when Barry, Cisco, and Harry went through it, it exploded.

While Barry, Harry, and Cisco were traveling through the breach, they saw a lot of amazing DC Comics easter eggs, including: future Oliver Queen who was aiming his bow and arrow with a metal arm (this version of Oliver will be in episode six of "Legends of Tomorrow,") the 1990s version of "The Flash" featuring the actor who plays Barry's dad, John Wesley Shipp, Supergirl herself Melissa Benoist (Grant Gustin will be visiting "Supergirl" at the end of March,) Jonah Hexx (who will be guest starring on episode 11th of "Legends of Tomorrow,") a Legion of Superhero ring, and the formidable Gorilla Grodd. If all of those easter eggs weren't enough there are at least a dozen more to cover in this episode.

Once they reached Earth-2, Barry and Cisco quickly realized they were literally "not in Kansas anymore." Case and point as to why Earth-2 was so different: A member of the Snart family was mayor, Zoom had the whole city on curfew, and Henry Hewitt, a.k.a. Tokamak (Demore Barnes,) the metahuman who wanted to become the next Firestorm, was Harry Wells co-worker at Earth-2 S.T.A.R. Labs! Barry discovered even more unusual Earth-2 facts when he disguised himself as Earth-2 Barry, including: He and Iris were married (just like in the comics,) Floyd Lawton a.k.a. Deadshot (Michael Rowe.) was actually Iris' partner at the Central City Police Department and was a terrible shot, and Captain Singh was a criminal. And that's not all. When Barry reluctantly went home with his wife, Iris, he received a phone call from his mom, Nora Allen. Nora Allen was still alive and well on Earth-2, and even though Barry didn't get to see her, hearing her voice made his heart break. This scene was very reminiscent of the "Flashpoint" comic, as Barry's mom was still alive in that version of reality.

Here's a better look at that very Justice-y speed dial. #TheFlash pic.twitter.com/WNl8tkJWCM- Atomic Geekdom (@AtomicGeekdom) February 10, 2016

The phone that Barry used to talk to his mom also had some amazing easter eggs on it. The phone had six names on speed dial: Dad (Joe West,) Mom and Dad (Nora and Henry Allen,) Eddie (Thawne?) Bruce, Hal, and Diana -- Bruce Wayne (Batman,) Hal Jordan (Green Lantern,) and Diana Prince (Wonder Woman.) While these names have no official bearing on the show, they were fun easter eggs to spot in the episode. Nora Allen even name-dropped Atlantis, home of famed Aquaman and Mera. The name at the top of the list was dad, which must mean Joe West, who, as Barry found out later that evening, was a lounge singer at the "Jitterbug" (the Earth-2 version of Jitters.) This was a fantastic character for Jesse L. Martin to play because he has had a long career on Broadway and has an amazing singing voice.

While Barry and Iris enjoyed listening to Joe sing, their party was crashed by two familiar faces: Caitlin Snow and Ronnie Raymond (Robbie Amell.) Sadly they were not there to be friendly -- they were there to kidnap The Flash and take him to Zoom. As they stepped into the room, Barry was amazed to see that they were not like his friends on Earth-1, but they were villains, going by the names of Killer Frost and Deathstorm. Frost exhibited some her powers earlier in the episode when she impaled a man with her icicle blades and her frozen kiss of death. The only thing redeeming about these characters was that they found love in each other, as Ronnie was the only man Killer Caitlin could kiss and not freeze. Barry and Deathstorm then chased each other around Central City, but not before Deathstorm hit Joe with a fiery blast that landed Joe in the hospital. While Barry talking to his mom was a sad moment, watching Earth-2 Joe West die was by far the saddest moment of the episode and something that hopefully never happens on Earth-1.

In an effort to incapacitate Killer Frost and Deathstorm, Cisco made a weapon that could take her down. Cisco, Iris, and Floyd went to Killer Frost and Deathstorm's hideout and confronted them. Cisco even asked Deathstorm if Martin Stein was in his head, and sadly he was, but Deathstorm never lets him out. Cisco also scolded Killer Frost and Deathstorm for working for Zoom. As it turns out, they didn't work for Zoom, they worked for evil Cisco! Cisco and evil Cisco introduced themselves to each other as Vibe and Reverb. Reverb tried to play into the classic "join me and together we can rule the galaxy" trope, but Cisco didn't give into it. The only thing that amazed Cisco about Reverb was his powers.

As the showdown resumed, Iris shot Killer Frost, Reverb injured Lawton, and Deathstorm and Reverb teamed up against Barry. Cisco and Reverb even came to blows, after Reverb hit Barry with his super vibes. Deathstorm and Reverb knocked Barry out and delivered blow after blow, even after Killer Frost warned them that Zoom wanted Barry alive. Because of their insubordination, Zoom killed both Deathstorm and Reverb. Earth-2 Caitlin had to watch Ronnie Raymond die again, and even on this earth, Cisco got his heart vibrated to a deadly level by a speedster. It would appear that some things remain the same no matter what earth your on.

In the final scene, Barry woke up in a glass box, surrounded by other imprisoned people. One man was wearing a metal mask. Jesse was there too, and when Barry promised to rescue her, Zoom told Barry not to make promises that he couldn't keep. Zoom's line about promises felt so personal, as if Earth-2 Barry once made Zoom a promise that he couldn't keep. Considering the episode revealed Earth-2 doubles for Ronnie, Joe, Barry, Caitlin, Iris, and Cisco, none of those people can be Zoom. The only people the episode did not reveal were Eddie Thawne (Rick Cosnett) or Henry Allen. Considering they both exist on Earth-2, they are still possible candidates for Zoom's true identity.

Next week's episode is titled "Escape from Earth-2" and will wrap up this story line, hopefully with Barry and Cisco returning to Earth-1 safely. Check out the synopsis and trailer for that episode below. "Escape from Earth-2": On Earth-2, the team races to find Zoom's lair and asks for help from the most unexpected source. Meanwhile, back on Earth-1, Caitlin (Danielle Panabaker) rushes to perfect Velocity-9 so that Jay (guest star Teddy Sears) can stop the Geomancer (guest star Adam Stafford).

"The Flash" airs Tuesdays at 8 p.m. on The CW.