Filming began that June, and production was shut down in March 2020 due to the COVID-19 pandemic, leaving the season with only 19 episodes.

Melissa Benoist stars as Kara, with principal cast members Mehcad Brooks, Chyler Leigh, Katie McGrath, Jesse Rath, Nicole Maines, and David Harewood also returning from previous seasons.

They are joined by Azie Tesfai and Andrea Brooks, who were promoted to the main cast from recurring status in the fourth season, LaMonica Garrett, who previously appeared as a guest actor in the fifth annual Arrowverse crossover and the fifth season, and new cast members Julie Gonzalo and Staz Nair.

Elsewhere, Malefic takes control of Alex, but she is saved by Kara and J'onn and seemingly send him to the Phantom Zone.

Brainy and Nia reconcile their relationship and James leaves National City to take over his hometown newspaper.

As the Crisis begins, Brainy detects an anti-matter wave approaching Argo City, so Kara warns her mother Alura Zor-El, her cousin Clark Kent, and his wife Lois Lane.

Meanwhile, on Earth-1, Harbinger brings Barry Allen, Kate Kane, Oliver Queen, Mia Smoak, Sara Lance, and Ray Palmer to Earth-38 and rescues the Kents.

As Harbinger briefs the heroes on the Anti-Monitor, the Monitor raises a quantum tower to impede the anti-matter wave while the DEO and Lena work to evacuate Earth-38.

In preparation, Oliver passes the mantle of Green Arrow to Mia but, when he learns Barry is fated to die, he argues with the Monitor over the deal they made last year.

[42] Rovner said the rift between Kara and Lena was something the writers had been building towards for a number of years, with the fifth season serving as the "long-awaited payoff".

[43] Main cast members Melissa Benoist, Mehcad Brooks, Chyler Leigh, Katie McGrath, Jesse Rath, Nicole Maines and David Harewood return as Kara Danvers / Supergirl, James Olsen, Alex Danvers, Lena Luthor, Querl Dox / Brainiac 5, Nia Nal / Dreamer, and J'onn J'onzz respectively.