This week it’s a Glee reunion (with a Smash cameo) when Supergirl meets The Flash in "World’s Finest," guest starring Grant Gustin as Barry Allen. With the two most joyful of heroes teaming up, this episode gives us a lot of heart, a lot of laughs, and a whole lot to love.

When Supergirl finds herself feeling overwhelmed while facing not one villain but two, and still working towards earning back the city’s trust after everything she did when poisoned with red Kryptonite, she gains a new ally in The Flash. But Livewire and Silver Banshee may be more than a match even for these two heroes. And all the while, they also need to find a way to send Barry home.

This was an incredibly well acted episode, with our first shout out going to Mehcad Brooks as James Olsen. We see a very new side (or two) of James this week, and Brooks is clearly enjoying the chance to stretch his acting muscles.

Grant Gustin and Melissa Benoist have great chemistry and are so much fun to watch together. They may have been enemies on Glee, but they mesh well as allies on Supergirl. Jeremy Jordon brought much of the episode’s humor and heart this week as Winn, who is a far more interesting character now that he’s not just mooning over Kara. And Italia Ricci’s Siobhan Smythe has been building for weeks into this delicious villain, she nails the development perfectly.

But seriously, this week (as well as every week) really belongs to Calista Flockhart’s Cat Grant. Cat is easily one of the best characters on television, largely thanks to Flockhart’s impeccable performance. Flockhart once again balances the humor of Cat’s over the top attitude and behavior with the layers of compassion and love she never can keep totally hidden. Cat continues to be the highest of the show’s many high points.

"World’s Finest" is one of the funniest episodes of Supergirl to date. It may even be the funniest overall, though with plenty of drama and high stakes to go around as well. It is everything that you could want from this crossover, and then some. Here’s to hoping there is another crossover again in the near future. If they are going to be this good, then we can’t wait for the next one.