In December 2018, during the end of the annual Arrowverse crossover "Elseworlds", a follow-up crossover was announced titled "Crisis on Infinite Earths" based on the comic book series of the same name. The crossover features Tyler Hoechlin reprising his role as the Earth-38 Clark Kent / Superman from Supergirl, while Routh portrays another version of Superman. It took place over five episodes–three in December 2019 and two in January 2020, with Legends of Tomorrows episode concluding the crossover. The Legends of Tomorrow episode is considered a special episode, and not the series' fifth season premiere.
