is supergirl in the same universe as flash and arrow
Arrowverse The first television series was Arrow, based on the character Green Arrow, which debuted in October 2012. The universe was expanded with the series The Flash in October 2014, which is based on Barry Allen / Flash. The universe expanded further in August 2015 with the animated series Vixen on The CW Seed, and again with the live-action team up series Legends of Tomorrow in January 2016. The franchise has also crossed over with DC Comics television shows which air on other networks; Arrow crossed over with the short-lived NBC series Constantine in the former's fourth season, while there have been multiple crossovers with the Supergirl TV series, primarily following its move from CBS to The CW.
Duet (The Flash) "Duet" is the seventeenth episode of the third season of The CW television series The Flash, which aired on March 21, 2017. The episode was written by Aaron Helbing and Todd Helbing from a story by Greg Berlanti and Andrew Kreisberg, and was directed by Dermott Daniel Downs. The episode features a musical crossover with Supergirl and reunites Grant Gustin and Melissa Benoist with their former Glee co-star Darren Criss, who portrays the Music Meister. Jesse L. Martin also reunites with Jeremy Jordan, with whom he previously worked in the 2012 musical film Joyful Noise. The story begins at the end of the Supergirl episode "Star-Crossed", which aired on March 20, 2017, which saw Kara Danvers / Supergirl (Benoist) being put into a coma by Music Meister, with Mon-El (Chris Wood) and J'onn J'onzz / Martian Manhunter (David Harewood) bringing her to Earth-1 in hope that Team Flash can save her.