Other mistake: Barry comes back to his home, replaces the fuse in the fuse box, flips the handle (begs the question of why remove the fuse AND turn off the switch, but whatever), and within 2 seconds every screen in the place is lit up. Sure, a TV might come on that fast, but plenty of those screens are showing data, analysis, etc, running off computers, which would take longer than that to boot up and get everything running.

Zack Snyder's Justice League (2021)
Trailers
Directed by: Zack Snyder
Starring: Ben Affleck, Amy Adams, Jared Leto, Henry Cavill, Gal Gadot, Ezra Miller, Ray Fisher
More trailers
More mistakes in Zack Snyder's Justice League More quotes from Zack Snyder's Justice League More trivia for Zack Snyder's Justice League More questions & answers from Zack Snyder's Justice League
Jonathan Kent: You were sent here for a reason. And even if it takes you the rest of your life, find out what that reason is.
Trivia: Director Zack Snyder has a cameo at the coffee shop while Lois is outside of it.
Question: When did Martian Manhunter get to Earth, why did he assume Martha Kent's identity, and where is she during Justice League?
Join the mailing list
Separate from membership, this is to get updates about mistakes in recent releases. Addresses are not passed on to any third party, and are used solely for direct communication from this site. You can unsubscribe at any time.
Check out the mistake & trivia books, on Kindle and in paperback.
Answer: Martian Manhunter is played by Harry Lennix, who also plays General Swanwick, a character who appears in Man of Steel and Batman v Superman (and we can see he transforms back into Swanwick he leaves), revealing that Swanwick was Martian Manhunter the whole time, so the indication is he got to Earth before Man of Steel. He assumed Martha's identity to speak with Lois, specifically to have a heart to heart with her as she is depressed due to Clark's death. Martha is present every other time we see her, when she leaves the Kent home at the beginning and when she reunites with Clark later on. This scene was the only time Martian Manhunter used her identity.
Casual Person