Continuity mistake: At the Fortress of Solitude, Superman is shown trying to cure cancer. The large computer he is using has three screens in a semicircle around it. Throughout the whole scene there with him, the robot, and Lois, the screens keep changing positions or vanishing all together. (00:07:30)
Continuity mistake: As Clark is telling Lois that he's off to the airport to leave for Afghanistan, she is putting her report on Lex Luthor's "charity organization" in the shredder out of frustration at Perry White. There is a painting of a landscape on the wall behind the paper shredder, and there is a blue file cabinet next to Lois and the shredder. The file cabinet is about the same height as Lois while she's sitting. It cuts to Clark, and then back to Lois in a closer shot, and suddenly the painting on the wall has vanished and the file cabinet is much taller. (00:04:40)
Continuity mistake: Just before Clark walks up to Lois' desk to tell her he's off to the airport, you see a view of part of her desk as she's throwing papers away. You see her phone, and there is nothing else visible except the side of her computer as the camera pans up. Then after Clark goes to the elevator, a different angle of her desk is shown at her cubical. Suddenly the phone is in a different position, a pencil appears, and a yellow sheet of paper is hanging off the side that was not there a moment before and is wedged under the phone. (00:04:30)
Continuity mistake: As Lois is ranting to Perry White about her report, the door to Perry's office is behind her. You can see the writing of "PERRY WHITE EDITOR" on the door through the glass, backwards as it is on the other side of the door. The edge of the letters of the P in Perry and the E in Editor are about 3 inches from the edge of the window by my best guess. A few shots later, it cuts to outside this door showing Jimmy Olson eavesdropping on the conversation from the other side of the door. Now suddenly the letters are closer to the edge of the window, now being about only an inch. The font style of the text on the window also changes slightly. (00:03:40)
Continuity mistake: When Perry White picks up Lois' report, it is on the left side of the computer from his perspective. He keeps it in his left hand and does not move from that spot and the computer is shown in the next spot as being on the right edge of the desk. Yet when he slaps it down in the side shot, his arm and paper are suddenly to the right of the computer. (00:03:35)
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: 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: After throwing the guy out of the driver's compartment of the laser drill, Doomsday jumps down and smashes a guy into the ground, leaving a hole. During this same shot, Doomsday picks up the laser drill rig and crushes another guy with it, and suddenly the hole has vanished. (00:10:30)
Revealing mistake: When Tess walks into Lex's office, he is standing at his window looking out, or at his reflection. When he turns around and begins typing on a hand held device for the cure to Muscular Dystrophy, he at first only turns half way around, being 90 degrees and now facing parallel to the window. However, his reflection turns around 180 degrees and like he has his back to the window. (00:06:40)
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)
Continuity mistake: After Perry White tells Clark to write articles when he's out of the country, Clark reaches over to his desk and picks up a purple lunch box with his right hand. His left hand has his bag in it. He then sees the picture of his mother, Martha, and reaches out with his right hand to pick it up and look at it. The lunch box is gone. He sets the photo back down and turns off his computer, and you see his left hand still holding nothing but his bag, and he turns to walk away. After he gets off the elevator, he suddenly has the lunch box again. (00:04:25)
Continuity mistake: Clark is packing things from his cubicle when Perry first speaks to him. In the first shot of Clark, you can see the items on the desk of his cubicle, mostly the computer, which is very near the edge. When it cuts to a close up of him putting stuff in his bag, a cup full of pencils and pens appears next to his computer. Then as he is setting down the picture of his mother, the cup has more in it, and the things hanging on the wall of his cubicle change. (00:04:00)
Continuity mistake: Doomsday grabs Superman and pounds his gut hard enough to splatter blood on Lois' face. In a side shot of her and Jimmy, the blood streak on her face has two drips on it, and is curving up. It cuts to a close up of her, and suddenly there is just one drip, and it is curved down. Her mouth is also suddenly closed. (00:25:05)
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