Tyler Hoechlin was set to reprise his role as Clark Kent/Superman in the finale, but wasn't able to due to scheduling conflicts.
The first time that Melissa Benoist sang as Kara was in Duet (2017). The song that she sung was "Moon River."
This is the last episode of the series.
The most successful costumed superheroine show of all time, far eclipsing any other female comic book TV adaptations in terms of both seasons and episodes.
Kelly mentions "agent of chaos." "Agent Of Chaos" is what The Joker calls himself in The Dark Knight (2008).