Warning: The following contains SPOILERS for Superman & Lois seasons 1 & 2.
There were a number of hints and clues that Superman & Lois was not set on Earth-Prime, the central world of the Arrowverse. The ending of Superman & Lois season 2 officially confirmed what many eagle-eyed viewers had guessed from various context clues, firmly establishing that Superman & Lois is set in its own unique universe. This revelation has resulted in a split in the fanbase, however, with many viewers annoyed thatSuperman & Lois is set in a different universe after all the effort made to bring all of The CW's superhero shows into a single shared setting during the Crisis on Infinite Earths event.
Superman & Lois showrunner Todd Helbing claimed (via TVLine), that Warner Bros. and DC made the decision to set Superman & Lois apart from the rest of the Arrowverse while they were in the middle of Superman & Lois season 1. This was largely due to the complications brought on by the COVID-19 pandemic making it more trouble than it was worth to try and tie the various Arrowverse series together. Unfortunately, Helbing was not allowed to make this change plain until the Superman & Lois season 2 finale, leading to accusations of treachery and lying from incensed viewers on social media.
Related: Superman & Lois Confirmed NOT To Be Set On Arrowverse Earth-Prime
Helbing's story is backed by a number of signs that Superman & Lois season 1 was originally intended to be set on Earth-Prime. Chief among these is a cut Easter egg scene in which Lois handles a photo of herself, Clark, and Kara Danvers, and John Diggle's Superman & Lois season 1 cameo, which referenced Crisis on Infinite Earths and the finale of Arrow. Despite this, there were many more
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