

A number of actors and characters from previous Arrow seasons returned to reprise their roles, since Arrow 's episode doubled as its 100th. In "Invasion!", the main cast members of each series appear in (at least) their own series Melissa Benoist appears as Supergirl in the entire crossover. The premise and episode titles were also announced in September. By the following September the scripts for each episode were written, and were filmed in October 2016. In the crossover, Barry Allen recruits Kara Danvers / Supergirl from Earth-38 to Earth-1 to help his team, Oliver Queen and his team, and the Legends to defeat the alien race known as the Dominators.ĭevelopment of a crossover between the three series and Supergirl began in May 2016, when it was learned that Supergirl would move to The CW from CBS for its second season.

Each of the main three episodes were titled "Invasion!". Events at the end of the Supergirl episode " Medusa" on November 28, 2016, marked the beginning of the crossover, which began on November 29 with The Flash, continued on Arrow on November 30, and concluded on Legends of Tomorrow on December 1. " Invasion!" is the third Arrowverse crossover event, with episodes of the television series The Flash, Arrow and Legends of Tomorrow on The CW, and is inspired by the 1989 comic miniseries Invasion!.
