Character mistake: As Lex is studying the recording of when Superman's body vanishes, he says "A 19 second black out at 3:47 AM." But the clock on the video shows it goes from 3:47:05 when the blackout starts, to 3:47:26. The blackout was 21 seconds, not 19. (00:45:55)
Continuity mistake: The live news broadcast of Superman's interview after his resurrection shows it broad daylight in Metropolis. When Martha Kent sees this at her farm, although being in the same state, it is pitch black night time outside at her house. (00:40:10)
Continuity mistake: Lois uses a backpack to hit the doll with the knife. It hits the windshield of the school bus and falls to the ground, glass all around it. When Lois steps on it to break it, the glass around it vanishes. (00:36:45)
Continuity mistake: The curtains on the door of the Kent farm keep changing colors in the scene where Lois talks to Martha Kent at the door. Shots from behind Lois show the curtains a pale white color, but the close ups of Martha show them as red. And in the reverse angles from behind Martha, they appear a pale pinkish orange. (00:31:00 - 00:32:30)
Continuity mistake: When Perry White is talking to Lois about Clark not calling or emailing, Lois is reading the newspaper about Superman's death. She has it opened up fully. But after the camera shows Clark's computer, Lois still in the shot with the newspaper open, it cuts back to Lois and suddenly she has it folded over. (00:30:25)
Continuity mistake: When Superman emerges from the smoke and rubble after smashing Doomsday down with reentry, he is mortally injured and his suit is tatted, torn, and burnt. The shoulders are notably torn and his left shoulder looks burnt. Then after Superman dies in Lois' arms, the camera pulls back and suddenly his suit is in perfect condition, aside from the missing cape. (00:26:45)
Factual error: Doomsday sees a little girl crying in the street and stops his assault on Superman to go attack the little girl. Superman quickly grabs Doomsday around the waist and jumps, rocketing them both up into space before Doomsday can crush her. The shockwave of this jump is seen as the tremendous force causes the street they were standing on to break apart and rubble fly. Yet the little girl is completely unaffected by the shockwave, it passes right through her and she is only feet away from the crater now left from Superman jumping up with Doomsday. (00:25:20)
Continuity mistake: After Doomsday and Superman get out of the subway, Superman flies into him before the monster attacks more civilians. But Doomsday counters and smashes Superman into the ground. Superman is then trying to get up and is on his hands and knees. But the angle changes and suddenly he is on his side. Also the car beside Superman vanishes between shots. (00:23:45)
Continuity mistake: Doomsday throws Superman at a wall and pile of rubble. There is a red car stuck in this rubble. Doomsday then begins pounding on Superman's head and smashing him further into the wall. But in the shot where Superman falls out of the wall, the red car has vanished. (00:20:10)
Continuity mistake: Doomsday breaks through the ice and slams down on Superman, and when he blocks the attack, the ground cracks under Superman's feet and makes a hole. After Superman pushes Doomsday away and then Doomsday charges back, the same spot is visible. Suddenly the hole and cracks in the ground have vanished, the tank is suddenly closer to the rubble, and the buildings in the background have changed up, most noticeably the windows on the blue building. (00:18:35)
Continuity mistake: After Superman and Doomsday first being their fight, Superman uses his breath to start freezing Doomsday. But the beast still walks towards Superman as he is being frozen. A shot of Doomsday's feet show he walks onto ground that is already covered in ice as his feet begin to freeze. But the shot cuts to a side angle and suddenly the ground Doomsday is on is not frozen. (00:18:10)
Revealing mistake: Dr. Murphy and another male worker at Project Applecore make fun of Lex Luthor and begin laughing at their own joke. As the guy laughs, one of the squares on the side of his hard hat does not move with the rest of him. His head, hat and the other squares bounce up and down as he laughs, but that one square stays put. (00:06:10)
Continuity mistake: When Superman and Lois kiss to make up for their first fight, she has her hand on his shoulder, about an inch away from his neck. It cuts to a close up, and suddenly her hand has moved to being half way on his neck. (00:15:40)
Continuity mistake: The driver of the gas tanker kicks around frantically as Doomsday is ripping him out of the truck and kills him. His foot goes through the driver's side of the windshield, shattering it. But the passenger side is unharmed because it is a separate window in this model of truck. The truck plows through the guard rail after Doomsday kills the driver and plummets to the ground, the passenger side of the windshield still fine. But in the shot of it just before it hits the ground, it is suddenly cracked as well. (00:14:55)
Continuity mistake: As Doomsday is ripping the roof of the cab of the gas tanker, his mouth is open. It cuts to a close up of his face and it's suddenly closed. (00:14:50)
Continuity mistake: When Doomsday looks up and sees a gas tanker driving by, it only has two lights on top of it. When it cuts to a close up, it has 4 lights on top. Also in the distance shot, the window and side view mirror on the passenger side are missing, but appear in the close up. (00:14:35)
Continuity mistake: As Lois is walking up to Superman from behind while they're both in red robes, she says "Look, I know who you are. Why can't you just tell me?" Superman's head is straight in that angle. But it cuts to a closer shot and his head is suddenly tilted to the side a little. (00:13:35)
Revealing mistake: When Project Applecore is first shown, a laser drill busts up some rocks. A forklift-like vehicle with a bulldozer front swoops by and picks up the rubble. Then the vehicle turns 90 degrees and heads away, but with none of its wheels ever turning. (00:05:20)
Continuity mistake: When Doomsday breaks out of his ship and starts killing the people at Project Applecore, the area around the spikes on his body are the same color as his skin, just slightly lighter gray. But after throwing the laser drill rig at a worker, he jumps at and punches two more guys. The hand held camera one guy is using fades out for a moment, then back in. Now suddenly the area around Doomsday's spikes have turned blue. (00:10:45)
Continuity mistake: Just before Clark is shown getting into the elevator at the Daily Planet, the light arrows above the elevator are shown as the down arrow lights up. It cuts to Clark getting in the elevator and suddenly there is a white bar between the two arrows. (00:04:50)
Chosen answer: When they call Doomsday a machine, they don't mean a literal machine. Just that he was built/designed. The comics were much the same. Doomsday was created by placing a baby on the most dangerous planet in the universe, and cloning that baby every time it died, forcing it to adapt. Doomsday eventually escaped this torture.
MasterOfAll