Invasion!

Invasion! is the name of the third annual Arrowverse crossover event between Supergirl, The Flash, Arrow and DC's Legends of Tomorrow. The crossover aired over four nights from November 28th to December 1st, 2016.

Trivia

 * The crossover was marketed as Heroes vs Aliens.
 * There are eight characters who appear throughout the entire "Invasion!" crossover (not counting "Medusa," which takes place entirely on Earth Thirty-Eight and only sets up the story at the end of the episode). The characters are Oliver Queen/Green Arrow, Barry Allen/The Flash, Kara Danvers/Supergirl, Ray Palmer/The Atom, Sara Lance/White Canary, John Diggle/Spartan, Felicity Smoak/Overwatch and Cisco Ramon/Vibe. The only characters who appear in all the "Invasion!" episodes and are Barry, Kara, and Cisco.
 * Notably, all eight of these characters are featured in the posters highlighting the event (shown below).
 * Josh Segarra and Matt Letscher were the only series regulars who didn't appear in the crossover.
 * This crossover is the first crossover to include Supergirl and DC's Legends of Tomorrow.
 * Even though the crossover was marketed as a "4-night crossover event", the first part didn't focus on the crossover until the last scene.
 * Ray Palmer states that Kara resembled his cousin. This is a reference to Brandon Routh's role of Superman (who is the cousin of Supergirl) in the movie Superman Returns.

"To be continued on" cards
Invasion! (ujednoznacznienie)