Continuity mistake: When Flash calls himself "a snackhole", he holds the pizza carton with the hand at its corner, then more towards the middle. (01:33:30)
Continuity mistake: Hippolyta is running away from the chamber of the Box and screams to ready the hammers. Notice how she is running in the middle of the corridor and if anything her steps bring her closer and closer to the line between the stones running exactly in the middle. A parademon bludgeons the other amazon that is following Hippolyta, and you could see him in the background earlier too preparing to do so, but now the queen is running towards the right side of the entrance, leaving room for the camera. (00:29:45)
Continuity mistake: When Wonder Woman breaks through the door, the left side flies off sliding on the floor almost all the way to the couch in the reverse shot, but is closer to WW in the next. (00:21:40)
Continuity mistake: When Flash talks to his dad at the end of the movie, he puts a paper against the security glass. The paper is tilted towards his right a bit, but in the reverse shot it's tilted more heavily and in the opposite direction, and so it stays for the rest of the scene. (03:37:05)
Continuity mistake: When Wonder Woman readies her sword (which makes also a sound) in front of the portal to Apokolips, wind blows her hair behind her back in the frontal view. Cut to the view from the back, and the hair is in front of the shoulders. (03:24:55)
Continuity mistake: When Lois randomly appears on the battlefield, she drops the handbag while one of the policemen tries to restrain her. The bag is behind the original position when the shot changes. (02:46:50)
Continuity mistake: When Wonder Woman goes to the kettle, Alfred is fixing circuitry in the background. He raises the tool in his right hand all the way to his nose almost, but in close-up he is still using the tool on the glove. (01:34:10)
Continuity mistake: Bruce Wayne hands Barry Allen a print of the security camera's incriminating frames. He holds the paper by the side in the first shot, but from the top in the reverse angle. (01:31:15)
Continuity mistake: During Victor's flashback, he scores a diving touchdown cushioning the fall with the right hand that is instead raised close to his body under the other angle. (01:19:05)
Continuity mistake: Steppenwolf begins to synchronize the Mother Boxes, and the event is perceived in Themyscira as well. The amazon that spots it has her left arm straight then bent in the reverse shot. (03:04:55)
Continuity mistake: After the gravedigging scene, a man in an orange coat tells Dr. Stone that the contamination tests came out negative. He is holding the clipboard by his side, in front of him, by his side again. (02:25:25)
Continuity mistake: Hippolyta shoots an arrow at Steppenwolf. She then reaches for another one on the ground and you can see her in the background ready the next one, but at the cut she has yet to be ready. (00:35:00)
Continuity mistake: The Queen passes the box to the Amazon on horseback holding it with the left hand on its top face in one shot, the side in the next. (00:31:30)
Continuity mistake: The Queen and Euboea are knocked off the horse by Steppenwolf. The Queen is face down, with the scabbard of her sword pointing up and aside of the mantle; next shot and the scabbard is not visible, just the mantle. (00:34:30)
Continuity mistake: Bruce pulls out of his jacket a wad of bills that stands straight upright, is significantly curled down in the next shot, and is more straight again in the following and when held horizontally as the kid nabs it. (00:11:25)
Continuity mistake: The village chief holds the calling card of "Bruus Vein" in a different way in each shot (lower corner, side, lower corner, upper corner). (00:09:05)
Continuity mistake: During the gravedigging scene, Aquaman offers Diana a swig from his flag, who turns it down. Momoa lowers his arm in one shot, and Gadot turns towards the others. In the background in the next shot, Momoa is lowering again his arm, and she is looking ahead. (02:22:55)
Continuity mistake: Alfred notices in his drink the disturbance caused by Superman's approach and pauses his work to stare at it, but in the next shot when Supes lands he is still working on the engine. (03:17:25)
Continuity mistake: Queen Hippolyta turns around and rushes to the rescue of an amazon that was running behind her escaping the Cage; notice how in the wide shot the girl turns from the prone position bringing the sword towards the parademon, but in the close-up the sword is facing the side. (00:29:50)
Continuity mistake: The Amazons are dogpiling Steppenwolf as he tries to reach for the box. One of them in the quasi-POV shot has a big quiver, but when she is sprinting to piggyback him the quiver isn't there. (00:29:00)
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.
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