Continuity mistake: Clark is thanking Bruce for the house. They both look in the distance at Lois and Martha; there are a couple guys fetching boxes near the carpenter, on both sides of the workbench, but they are nowhere to be seen in the new closer angle. (03:38:00)
Continuity mistake: When Aquaman like a true hero impales the bad guy from behind, Superman in the background is assuming the stance raising his fist. In close-up his arms are both lowered. (03:30:25)
Continuity mistake: Superman is pummelling Steppenwolf, and Darkseid's portal starts appearing. Wonder Woman turns around to face it in two shots; Aquaman in the first shot has the trident standing vertical, it's more slanted forward in the next. (03:24:45)
Continuity mistake: After the underground battle with Steppenwolf when they are finally joined by Aquaman, Wonder Woman sums up the situation with "All he needs now is the Lost Box of Men." Batman replies "If he doesn't already have it" in another shot, where Diana's hair is missing in front of her shoulder. (02:08:25)
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