Continuity mistake: Wonder Woman is on the statue on top of the Court of Justice building. She is holding the statue's sword at a different height in the two shots. (00:20:10)
Continuity mistake: Alfred is freaking out about Diana's sub-par tea brewing skills. He tells her that there's enough tea; Gal Gadot's fingers are in a different position on the container between shots. (01:34:30)
Continuity mistake: When Superman is hugging his family, Martha has suddenly at the cut her hand on his sleeve when he says "Listen, Ma..." (03:01:15)
Continuity mistake: When Aquaman dumps the sailor on the table, the patrons pull back their drinks at different times between shots (funnily enough, the continuity of this part is perfect in Whedon's version, who still picked a take originally filmed by Snyder). (00:51:20)
Continuity mistake: After Silas is killed, in the wide shot Cyborg is standing mostly upright in front of Flash. Cut to a closer shot and he's bent over. (02:51:45)
Continuity mistake: When Wonder Woman says "He's back" looking at the freshly resurrected shirtless Superman, the policeman by the patrol car is leaning against it differently compared to the previous line-up shot; he was lowering the hand with the radio, then talking on it. (02:40:40)
Continuity mistake: Steppenwolf sends away the parademons saying "This one will be mine" to confront Wonder Woman one-on-one. She says in close-up "I belong to no-one!" and her right shoulder is clear of hair, but in the previous shot she had hair right in front of that shoulder. (01:57:20)
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)
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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