Crisis on Infinite Earths: Part Three

The episode is the third part of the five-part crossover, ​.

Synopsis
Pariah enlists Black Lightning to help stop the Anti-Monitor after Flash-90 shares what he learned from his battle in "Elseworlds". With the help of Black Lightning, Barry, Cisco and Killer Frost come up with a plan that could save them all. Meanwhile, Iris has a heart-to-heart with Ryan Choi, while Oliver and Diggle return to an old familiar stomping ground.

Production
Shooting for began on September 24, 2019.

Trivia

 * During production, the episode was titled "Crisis on Infinite Earths: Hour Three".
 * This is the second time a character makes a sacrifice to save another character who is destined to died in an possible future. The first being H.R. Wells who sacrifice his life to save Iris by trading his life with her by getting killed by Savitar and the second being The Flash (Earth-90) who trade his life with Barry Allen to stop the anti-matter from destroying Earth-1.
 * Cress Williams became immediately starstruck when he stepped onto the set of the Arrowverse's forthcoming "Crisis on Infinite Earths" saga for the first time. "It's like going to a new school," says Williams, who took a break from shooting Black Lightning in Atlanta to spend a week working on the crossover in Vancouver. "I was just really overwhelmed at the pure number of people, and all of these supersuits. I was working with the Flash, two Supermen, most of the cast of The Flash, and some Arrow people. It was just a real hodgepodge, a full room."
 * For Guggenheim, it was important that Black Lightning appeared in the crossover for more than a glorified cameo, with Williams flying between the two filming locations on the weekends to maximize his availability while Black Lightning's writing staff reduced his role in several episodes to better accommodate his involvement.
 * Marc Guggenheim noted that the inclusion of Cress Williams' Black Lightning was a particularly challenging one due to the actor having to fly back and forth from Atlanta the primary filming location for Black Lightning to Vancouver, where "Crisis" was filmed. To make things even more difficult, logistically, Williams' costume, specially modified to give off a pulsating electric aura, was expensive to transport between the two filming locations to accommodate Williams' series and the crossover. "His costume is a very involved piece of equipment that has to be traveled [and] has a separate handler that has to travel with it," explained Guggenheim in an interview with Variety. "It was suggested to me at one point, by one of the money people, 'Does Black Lightning really have to wear his costume in the crossover?' He has to wear that costume. It just wouldn't be the same if he didn't."
 * Dina Meyer reprised her role as the Barbara Gordon/Oracle of Earth-203 in an uncredited voice cameo during the cold open.