Adapting an established comic book character for the small screen is challenging enough, so what’s it like adapting an entire world of them? Difficult, but if tonight’s new episode of The Flash is any indication, it’s also a crazy amount of fun.

This evening kicks off a two-part mini-epic that sees Barry Allen and Cisco Ramon journeying with Harry Wells to his home world of Earth-2. It’s an absolute blast of an episode—easily one of the best of the season. While we’ve caught glimpses of Earth-2 in the past, starting tonight, fans can expect to see more of Earth-2 than ever before and meet the very different doppelgangers of some of the show’s key characters. And that’s just the beginning. Both of the episodes are packed so full of Easter Eggs that even the sharpest-eyed fans are bound to miss a few.

“The ideas you have up on the board are just endless,” reveals Executive Producer Todd Helbing. “It’s really hard to narrow it down, but you just try to pick and choose what you think is the best.”

While not all of those ideas actually figure into the plot, several of them do. For example, in Earth-2, “Detective West” doesn’t refer to Joe, but Iris. Rather, Joe West makes a living belting out standards as a jazz singer. And speaking of Iris, she’s married on Earth-2…to Barry.

“I think the fans are going to go crazy over it,” says Helbing. “Barry’s been in love with this woman his whole life and I can only imagine what it would be like to go over to a different reality and find out that you’re married to them.”

The seeds of this otherworldly excursion were planted last week when Harry came clean to Barry about his deal with Zoom, but rather than punishing him, the Flash agreed to help him save his daughter from the evil speedster. Of course, as is to be expected, things don’t exactly go as planned.

“Barry, Cisco and Harry go over to Earth-2 with a definitive plan that goes awry,” Helbing teases. “They are left having to improvise. They find themselves in a completely different scenario than they anticipated and have a race for their life to get back.”

That race finds Barry coming face-to-face with his bowtie-wearing Earth-2 counterpart and finding himself on the wrong side of Killer Frost and Deathstorm, who have been tasked with eliminating “breechers” for Zoom. Of course, finding yourself in a high-stakes fight to the death with two of your best friends would give anyone pause, but that’s pretty much to be expected when taking trips through the multiverse. As Jay Garrick warns Barry, in Earth-2, down is up and black is white.

DC fans familiar with the comics are well accustomed to Earth-2, which for the past few years has been the subject of its own monthly title. However, while The Flash’s Earth-2 has some similarities, it’s very much its own animal, with a slick, retro look that stands out.

“We have this amazing production designer, Tyler Harron,” Helbing says. “I think the idea from the beginning was always this sort of art deco feel. That’s basically all we have to say to Tyler and he just blows everybody out of the water. It’s amazing the stuff that he comes back with. You get these sketches of Earth-2 and all the buildings, and what they’re going to look like. It’s amazing.”

Another thing that the producers feel is pretty amazing is Grant Gustin’s portrayal of his Earth-2 counterpart. Seen for only a brief sequence in the first half of the two-parter, Helbing promises he plays a much more substantial role in the second half.

“It was a lot of fun,” Helbing reveals, grinning. “Grant is just one of those actors who can do anything. His comedic timing is amazing. His physical presence and humor is amazing.

“Originally, we just felt like he should have this sort of Jimmy Stewart quality, but we really just gave Grant a few ideas and he just sort of took that upon himself and created this amazing guy that you get to see. People are going to have a lot of fun seeing Earth-2 Barry. He’s very entertaining.”

Still, it wouldn’t be an Earth-2 episode without a few things intact. Jay Garrick plays a major role, keep an eye out for a fun Justice Society nod and unsurprisingly, Barry eventually comes face-to-face again with Zoom in a confrontation that both leads into next week’s part two and kicks off a string of events and revelations that will eventually culminate in the truth about who Zoom is.

“The next couple of episodes it starts to unravel,” Helbing assures us. “You get to see what’s really going on.”

Which means you’re not going to want to miss it. No matter what Earth you’re watching it from.

Episode 13 of The Flash, “Welcome to Earth-2,” airs tonight at 8 p.m. (7 p.m. CST) on The CW.