Development Coming off "
Crisis on Earth-X", the previous year's
crossover, executive producer
Marc Guggenheim noted that the process to pull off that crossover had made each series' crews "pretty burned out", with them "feeling the effects of it literally a year after". This led the producers to want to take a year off from the yearly crossovers, but were convinced by
The CW to create another when they allowed the crossover to not be with all four series as "Crisis on Earth-X" had been. In May 2018, The CW president
Mark Pedowitz and
Arrow lead
Stephen Amell announced at The CW's
upfront presentation that
Batwoman, fighting alongside the other
Arrowverse heroes, would be introduced in the upcoming crossover. The fictional
Gotham City would also appear. Despite the inclusion of the character and city, the crossover would not include the television series
Gotham that airs on
Fox. That July, The CW was planning a potential standalone
Batwoman series after her appearance in the crossover;
Caroline Dries, who was creating and writing the potential Batwoman series, was expected to consult on the crossover. It was confirmed that
Legends of Tomorrow would not feature in the crossover.
Legends of Tomorrow co-showrunner
Phil Klemmer said because the crossover was being used to launch the Batwoman-led series, "it just became over capacity", and that because
Legends of Tomorrow would have a 16-episode season, the crossover would have been "a tonal speed-bump, or a departure, and we just don't have time to step away from our story this year". Despite not being part of the official crossover,
Legends of Tomorrow co-showrunner
Keto Shimizu revealed "Legends of To-Meow-Meow", the show's episode airing the week of the crossover, would be "crossing over with ourselves" through the use of alternate time periods, and Adam Tsekhman guest stars as Gary Green in the
Supergirl episode. At the end of September 2018, the title of the crossover was announced as "Elseworlds", sharing the name of the
Elseworlds imprint of comics from
DC Comics that takes place outside the
DC Universe canon. The producers initially considered titling it "Identity Crisis" but abandoned the idea because, according to Guggenheim, this title would be "false advertising, because we're obviously not doing the
Brad Meltzer,
Rags Morales Identity Crisis story".
Writing The story for "Elseworlds" was created by
Greg Berlanti, the executive producers and writers from each series,
Geoff Johns, and Dries.
Arrow showrunner Beth Schwartz referred to these people as "the Super Writers' Room", and noted that Marc Guggenheim, who was a consultant on
Arrows seventh season, had "taken the lead on the crossover", acting as the showrunner for it.
The Flash episode was written by Eric Wallace and Sam Chalsen, the
Arrow episode features a story by Caroline Dries and a teleplay by Marc Guggenheim, and the
Supergirl episode features a story by Marc Guggenheim and a teleplay by Derek Simon and Robert Rovner. The episodes' scripts were completed by mid-September 2018. Guggenheim said "Elseworlds" would have a long-lasting impact for the Arrowverse and "lays the groundwork for next year's crossover". At the conclusion of "Elseworlds", it was revealed that the next crossover would be "
Crisis on Infinite Earths" in late 2019, adapting the storyline from the
comic of the same name. The preceding episodes of each series feature "puzzling events" that lead to the events of the crossover. The same end-credits scene teasing the events of crossover was shown at the end of the episodes "
Bunker Hill", "
Unmasked", and "
What's Past Is Prologue". The scene also confirmed Earth-90 as the earth for the Flash from
the 1990 television series. Guggenheim said the tease was "cool because we've never ... setup the crossover in the previous episodes before". The tease was meant to be one of two options for the "Elseworlds"
cold opening. The writers could not choose which opening they would use; Guggenheim said someone decided to "take one cold open, move that and make that the post-credit tag, like the way
The Flash typically does, at the end of all three shows, and then have the other cold open at the beginning of hour one".
Supergirl co-showrunner Robert Rovner said the tease was only supposed to air with
Flashs "What's Past Is Prologue"; it was added to the other two episodes to make things easier for viewers because they "are coming to [the crossover] from our separate shows and we wanted something that [connects them together]". Stephen Amell announced that, unlike previous Arrowverse crossovers, this one would not be as extravagant, but more about "the characters and the story", focusing on Green Arrow, Flash,
Supergirl,
Superman, and Batwoman. According to Guggenheim, by focusing only on Green Arrow, Flash, and Supergirl, the writers "really had a chance to tell a story about the troika that we've never really been able to do before".
Legends of Tomorrow was not included in "Elseworlds" to highlight the amount of time Amell,
Grant Gustin, and
Melissa Benoist could interact. "Elseworlds" returned to the episodic format of the earlier crossovers, contrasting with the approach taken with "Crisis on Earth-X". Rovner said, "It's like a three chapters of one story, but they're all kind of unique to their own show";
The Flash showrunner Todd Helbing added, "
Flash kind of feels like a
Flash episode,
Arrow feels like an
Arrow episode, [and]
Supergirl feels like a
Supergirl episode". "Elseworlds" features Amell and Gustin portraying each other's characters. Gustin noted, "You're not going to see me playing Oliver Queen's mannerisms, or Stephen playing Barry's mannerisms. It's more being aware that for some reason we've switched lives and destinies. It's more the fun of the situational comedy that we keep finding ourselves in, and less us having a complete role reversal." Amell added, "there are elements of his personality I have to embrace, and there are elements of my personality that he has to embrace" for Oliver and Barry to defeat the threat. Supergirl is the only other character who can see the true identities of Barry and Oliver; Benoist said, "She inevitably becomes kind of a middleman because ultimately there's conflict between the two and they start butting heads". Schwartz said "Elseworlds" would not "feel quite as dark" as "Crisis on Earth-X" and that there was "a lot more fun to be had" in "Elseworlds". Other reality changes in the episodes include Barry and Oliver becoming wanted criminals known as the Trigger Twins. One reality change that Guggenheim and Schwartz considered to do was bringing Sara Diggle,
John Diggle's and
Lyla Michaels' baby daughter who got erased in
Flashpoint, back into existence, but they ultimately thought it wouldn't be as impactful as if they did it as part of the multiversal reboot in "Crisis". Including Superman, who Berlanti had permission to use before March 2018, in the crossover helped justify introducing Lois Lane to the Arrowverse because she was a character the writer of
Supergirl always wanted to introduce and "she organically fit" into the crossover story. With Kara "at a crossroads" after the events of "Bunker Hill", Rover said "the journey that she's on is kind of helped by Clark, who is returning from Argo [City] kind of on his own journey". Hoechlin also portrays John Deegan when he rewrites himself to be an antagonistic version of Superman. Gotham City in the crossover is considered "a failed city"; Batman "has been missing for several years", resulting in an increase in crime. Speaking of their adaptation of Gotham City, Dries called the city "not a happy place", "grimy", and "scary", adding, "Some people are thriving in [Batman's] absence because now they can start to do their own thing without the oversight. A lot of other people are suffering and they're losing hope, and the city itself and infrastructure is falling apart". Guggenheim called it "a dead city" and "practically a ghost town". While Batman is not seen in the crossover, the characters debate his existence; Oliver feels he is a myth and Barry believes he is real. Chronologically, Batwoman's appearance fits around "Who Are You", the fourth episode of
Batwomans first season that aired in October 2019, with Dries noting
Batwoman would be "officially caught up" to "Elseworlds" at the conclusion of that episode. "Elseworlds" includes many
easter eggs and nods to past DC television series and media. The line spoken by Psycho Pirate at the end of the crossover—"worlds will live, worlds will die, and the universe will never be the same"—paraphrases the tagline DC Comics used to advertise
Crisis on Infinite Earths in the run-up to its launch in 1985.
Casting In early August,
Ruby Rose was cast as Batwoman for the crossover and potential series. The producers noted Rose's passion in her audition and her "aura of cool, nonchalant, somewhat aloof, mixed with charming and thoughtful and funny that it just kind of all made sense for her to be Kate", according to Dries. Later that month, it was revealed that
Tyler Hoechlin would reprise his role as
Kal-El / Clark Kent / Superman in all three episodes and that the producers were planning to introduced
Lois Lane in the crossover. By mid-September,
Elizabeth Tulloch was cast as Lois Lane, Stephen Amell's wife
Cassandra Jean Amell was cast to portray
Nora Fries,
Jeremy Davies had been cast as antagonist
John Deegan, and
LaMonica Garrett was cast in the "prominent role" of
Mar Novu / Monitor. During filming in late October 2018, it was revealed that
John Wesley Shipp, who has portrayed Henry Allen and
Jay Garrick in the Arrowverse, would be reprising his role as Barry Allen / Flash from the 1990 television series. By the end of filming in early November,
Bob Frazer was cast as
Roger Hayden / Psycho Pirate.
Design In "Elseworlds", Hoechlin wears an all-black Superman suit while portraying John Deegan's antagonistic version of the character. This costume is similar to the one he wears in the comics after returning from the dead as part of the "
Death of Superman" crossover. Shipp's Flash costume from the 1990s series was recreated by
The Flash costume designer Kate Main, using the original costume as a reference.
Justin Hartley's
Green Arrow costume from
Smallville is seen in the opening on Earth-90. Guggenheim received permission from the
Warner Bros. archives to include it, but had stipulations that it could not be worn by anyone and could not get dirty. He said, "we put it on a dummy, so thereby we satisfied that loophole, and as far as not getting it dirty, hopefully whoever at archives provided it to us never actually saw that episode."
Filming Filming for
Elseworlds began on October 9, 2018. On October 17, filming for the Kent family farm occurred at the farmhouse used in the series
Smallville. The
Supergirl writers
pitched the
Smallville farm as the meeting point for Kara and Clark because, considering the characters' experiences at the start of the crossover, it was an "organic place for them to meet". A "derelict mental health facility" in Vancouver was used for the Arkham Asylum scenes. Scenes of Gotham City and
Wayne Enterprises were filmed in
Chicago, Illinois. Filming concluded on November 3.
Kevin Tancharoen directed
The Flash episode,
James Bamford served as director for the
Arrow episode, and
Jesse Warn directed
Supergirls episode.
Music In scenes featuring the Earth-90 Flash,
Danny Elfman's 1990s
Flash series theme is used, while the theme song from
Smallville, "
Save Me" by
Remy Zero, is used when Smallville on Earth-38 is first revealed. == Marketing ==