Trivia: Jon Cryer, who plays Lex Luthor, played Lex's nephew Lenny in Superman IV: The Quest For Peace.
Trivia: The way Deegan as Superman tries to break Barry's neck resembles Superman doing the same thing with Zod in The Man of Steel film.
Trivia: The way Clark smashes the coal to get a diamond resembles Superman 4.
Trivia: The hammer used by Lois is similar to the one used by Steel, another DC superhero.
Trivia: Although they play mother and son in this episode, Brenda Strong is only five years older than Jon Cryer.
Trivia: Kara and Barry slowed time by running around the earth, that resembles what Superman did in Superman the Movie.
Trivia: While the two Supermen are fighting, a girl calls one of them Bizarro, he is another enemy of Superman.
Answer: For one, it's usually cheaper to film in Vancouver because of the tax breaks. But all the CW Arrowverse shows (with the exception of "Black Lighting") are/were filmed in Vancouver. So it makes it easier and cheaper for sharing set designs, crossovers, etc ("Black Lightning" filmed in Vancouver during its crossover). Originally "Supergirl" wasn't part of the Arrowverse when it was on CBS, but it was too expensive to produce and wasn't reaching the wider audience the CW shows had. So CBS moved it to its sister company, The CW.
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