The Flash and Supergirl will have a Musical crossover event in 2017, and no, you are not dreaming. With Broadway vets Jesse L. Martin, Tom Cavanagh, Carlos Valdes and Glee star Grant Gustin on The Flash and Glee's Melissa Benoist and Broadway vets Jeremy Jordan and Laura Benanti on Supergirl—not to mention Arrow's John Barrowman and Legends of Tomorrow's Victor Garber —there is plenty of musical talent to go around. "Yes, there will be a musical crossover. There's going to be a musical pair of episodes in the back half of the year between Supergirl and Flash ," executive producer extraordinaire Bernanke announced at a panel discussing Supergirl, The Flash, Arrow and Legends of Tomorrow at the Television Critics Association summer press tour. "We have a number of people who can sing across all the shows who will be making some very exciting appearances in the back half of the year." While the tunes will likely be pre-existing songs, Berlanti said ...