Amell added that each episode feels like part of the crossover, rather than just an episode of Supergirl, The Flash, Arrow or Legends of Tomorrow.
According to Stephen Amell, the 2017 crossover between Arrow, The Flash, Supergirl, and Legends of Tomorrow – now officially titled “Crisis on Earth-X” – will not only be the Arrowverse’s biggest crossover yet, it will also feel like a “four-hour movie.”
Supergirl and Arrow will air on Monday and The Flash and Legends of Tomorrow will air on Tuesday.
In December 2014, The CW aired a two-episode crossover between The Flash and Arrow that thereafter became an annual event.