In the debut season of Supergirl, we saw the Flash entering the National city, jumping parallel dimensions and breaking time-space continuum.
In the episode, we saw both of them trying to outdo each other in a race, they took down Silver Banshee and Livewire. Flash is seen wearing Tachyon device similar to the one donned by Reverse Flash in season 1. He helped Team Kara to develop a way to keep meta-humans locked up so that they don’t need to take them to DEO every-time. Instead of calling him the Flash, they used “The Blur” which is what they called Clarke in “Smallville”. This particular episode saw the maximum TRP in the entire season which basically confirmed that Supergirl and Flash is a winning combination and has a stamp of approval from DC fans.
This time, they are planning for a special 2-part musical crossover which will join the mega CW-DC Crossover of superheroes. Greg Berlanti, the executive producer, said during the Television Critics Association press tour that “they’re going to be mostly preexisting songs, they’re going to try and include at least one original song per episode, and the two episodes will likely air sometime in the back half of the year.” Both Melissa Benoist and Grant Gustin have musical backgrounds as both the actors have appeared in “Glee”. Jesse L. Martin (Joe West) played the role of Tom Collins in Rent on Broadway, while Jeremy Jordan (Winn) appeared in Broadway production of Newsies and film version of “The Last Five Years”.
There is a speculation in TV circles that Joss Whedon (Director, The Avengers) is going to direct the Flash-Supergirl musical crossover. He directed the episode in Glee too which had both Melissa Benoist and Grant Gustin. Moreover, Kevin Smith is returning to direct an episode of Supergirl titled “Supergirl lives.”