As if anticipating backlash against the aggressively grim Batman v Superman, CBS's Supergirl invited the Flash over from The CW for a madcap superhero team-up caper.

With Supergirl's Melissa Benoist (Kara/Supergirl) and The Flash's Grant Gustin (Barry/the Flash) heading up the crossover event, "World's Finest" came complete with flirty banter, heart-to-hearts about what it means to be a hero, and sneering villainesses in askew Hot Topic wigs. The Flash might have been concerned about running so fast that he accidentally ripped through a dimension or three and left his own Earth — a thing he can do, because superhero — but at least Kara's Earth had plenty of action to entertain him while he was briefly stuck there.

The crossover was possible thanks to a couple different factors. Though Supergirl and The Flash air on CBS and The CW, respectively, their DC Comics connection means they're actually sister productions, underneath the umbrella of Warner Brothers. (Similarly, The CW is a corporate cousin of CBS, which makes a crossover between Supergirl and The Flash easier than one between, say, Supergirl and a show on NBC.) Also, both programs were created by Greg Berlanti, who came up with the story for "World's Finest."

Was "World's Finest" a success?

Alex: Yes. It's difficult to go wrong pairing human golden retriever Gustin with the impossibly likable Benoist. You'd have to actually work to put those two in a scene together and have it be bad.

One of the things I like best about the episode is the idea of taking something super-complicated like the DC multiverse — the theory that there are multiple worlds that are all vibrating at different frequencies, which keeps them separate from one another — and really leaning into how weird and preposterous it sounds. Because that idea totally is weird.

Caroline: The best endorsement I can give "World's Finest" is that even though I regularly watch The Flash, I haven't been watching Supergirl, and this episode made me regret it. Benoist is a ray of sunshine, and Calista Flockhart's icy magazine editor manages to cut through Supergirl's softest of soft lenses with her dry disdain.

Also, this crossover episode is incredibly fun. The Flash has been losing me lately with overwrought retreads of plots from previous seasons and a heavy dose of brow-knitting melodrama; it was a relief to see Gustin getting to play Barry Allen as the adorable doof he used to be, even if just for a single episode.

Favorite moment from the crossover?

Alex: Tornado/frost breath 2016! It's dopey and silly, but it totally works:

But my favorite moments are actually the quieter ones between Kara and Barry. There's a scene in which she asks for advice and he just tells her to "slow down."

It's a heartwarming exchange, one that gets at the loneliness Kara feels because she hasn't really figured out how to be a superhero. But it also gets at the joy she feels now that she finally has someone to relate to. She and Barry share a disarming amount of chemistry.

Caroline: How many of Calista Flockhart's lines can I nominate for "best dialogue of the episode"? Because I'm torn between her saying that Kara, Barry, and company looked like the attractive, multiracial cast of "a CW show" and turning down Bernie Sanders for hot yoga.

In all seriousness, though, watching Barry and Kara race at the very end of the hour was a delight. The rest of the episode was fun and everything, but I could have watched them running and beaming at each other for a full hour and been totally satisfied.

All my favorite moments were between Barry and Kara, thanks to their easy, grinning rapport.

In fact, Gustin and Benoist are so good together that their pairing makes Supergirl's insistence on pushing Kara and James Olsen's romance less believable. Sure, he's strapping, but come on: The Flash is grinning at Kara in a sun-dappled field, all crinkly eyes and dimples, and as far as I can see, her connection with James is a B-minus at best.

Also, in that field scene, Kara is about to throw Barry Allen back into a whole other universe. No one will know if they make out a little first! To paraphrase Cat: Get some, girl.

What do the Flash and Supergirl have in common?

Alex: What both shows do so well is hammer home that their heroes are good people who want to do the right thing and really enjoy doing the right thing. It's earnest and cheesy. But it's also hugely fun.

Caroline: The Flash has become a show I look forward to watching each week, because it embraces the inherent cheesiness of comic books. It lets the Flash zip around Central City to fight the world's corniest villains, and it usually doesn't take itself too seriously (though it's starting to do so in its current season, which is upsetting). Putting the Flash in Supergirl's world — drenched in white light and Technicolor backgrounds — makes perfect sense.

Do we like that Cat Grant (Calista Flockhart) knows Kara is Supergirl? Or does she know?

Alex: Cat learned Kara's secret in the fall finale. This was later jumbled up during an episode where Martian Manhunter (who has the power to shapeshift) appears and Cat sees Kara and "Supergirl" (Manhunter shapeshifting) at the same time in the same place.

I'm of the belief that Cat sorta knows Kara's secret. And it adds a fun dynamic to the show, because we no longer have to suspend our disbelief that people become face blind when you wear glasses. And Cat maybe knowing Kara's secret slyly changes the impact of lines like, "I can spot the extraordinary pretending to be a nobody."

Caroline: I didn't know for sure while watching the episode whether Cat knew Kara's identity — again, I haven't been keeping up with Supergirl. I know people in comics aren't supposed to see past glasses to the person underneath (nerds, amirite?), but it would just be impossible to believe that Cat wouldn't realize her assistant is the superhero they've been tracking and photographing for months.

And really, what it comes down to is that I, for one, would rather not live in a world where someone who drips disdain for Ramona Singer's fondue etiquette is an idiot.

Supergirl airs Mondays on CBS at 8 pm EST. The Flash airs Tuesdays on the CW at 8 pm EST.

Update: We updated the last question/response to include the Martian Manhunter episode.