Continuity mistake: When Jimmy is looking at the newspaper in the ally with Lois, there is a small trashcan behind him. It's an olive green color and is dented. Then after he throws the paper at Lois and begins to walk off, the can is now gray, larger, and no longer dented. (00:45:40)
Continuity mistake: Doomsday has a bone spike protruding up from each of his 4 knuckles. But when Doomsday grabs Superman by the head and draws back to punch him hard in the face, the spike on his thumb is missing. Superman catches his fist, and in that shot you can see two more of the spikes have vanished, and Doomsday only has one over his middle knuckle. (00:23:55)
Continuity mistake: When Doomsday slams Superman down into the subway, the hole they make in the street is right in the middle of a crossing. But a minute later in the film as civilians are walking up to the hole, there are no lines anywhere around it. Moments later after Jimmy takes a picture of the hole, the shot cuts to a far angle and now the hole is next to the crosswalk lines, and in that shot the stairway entrance to the subway station also vanishes. The road also becomes much wider with more lanes, and the red truck turns around. (00:22:40 - 00:23:25)
Continuity mistake: In the first shot it is seen, the fence of the power station that Doomsday is thrown at shows that gate part is slightly taller than the rest of the fence and has one sign on each door of the gate. But then moments later as Doomsday is plowing through the gate, it is now the same height as the rest of the fence, and only one sign is present, which becomes smaller and a darker color. Also two vehicles appear behind the fence that were previously not there. Also on the gate there is a sign on each side of it, but before it breaks there is a sign only on the right side. (00:22:30)
Continuity mistake: In Metropolis on the bridge, Doomsday grabs a soldier and breaks his neck and skull. In that shot, the soldier's arms are inside Doomsday's hand and his hair is a light brown or gray. But then when the shot changes as Doomsday begins to throw the soldier to the side, the soldier's arms are suddenly outside of Doomsday's hand, and his hair is now black. (00:17:10)
Continuity mistake: Lex runs from Dark Superman into the Rumpus room again and raises his hand to the control panel. It then cuts to a close view and suddenly his arm and hand are lower instantly. (00:59:55)
Continuity mistake: When Lex is running way from Dark Superman after the clone lab is destroyed, he runs down the same hallway that Lois and Jimmy came through moments before. The pattern of the tiles on the floor is different between these times. (00:56:25 - 00:59:45)
Continuity mistake: When Lois says that Lex is harvesting Supermen, the camera pulls back to show the rows of incubation chambers. The first row has infants, the second row, which they are looking at, has adult clones, and then the third row has infants again. But then when Lex confronts them, the camera changes to behind Jimmy and Lois with the first row on their right and the second row to the left with Lex next to them. The third row is shown behind them, but now the third row has adult Superman clones instead of infants like seen in the above shot. (00:57:35)
Continuity mistake: The first row of incubation chambers holding the Superman clones when Lois and Jimmy walk in are holding small undeveloped infant clones next to the control consoles. But after Dark Superman destroys the lab and breaks the consoles, it shows fully grown adult clones on the floor where the incubation chambers were just destroyed by the console. (00:57:00 - 00:59:30)
Continuity mistake: When Lois is walking down the hall way in Lex's building, she rounds a corner. A split second later, Jimmy rounds it following her. It then cuts to a close up of Jimmy and suddenly his hands are positioned on his camera differently. Also the lines at the bottom of the walk in the tile like area are less numerous. (00:56:25)
Continuity mistake: In the Fortress of Solitude while Superman is in recovery, the robot has him doing exercises to build his strength. The shot pans over to show him pushing up on a weight machine. There are several vitals reading patches on his torso with cords hanging from him, except for two additional patches on his stomach that have no cords. It then cuts to a close up of him and suddenly the pointless patches on his stomach vanish. Also the parts he is pushing up against with his hands are instantly significantly smaller. (00:56:10)
Continuity mistake: Once Lois and Lex begin to kiss, Lois puts her arms around his neck and back with her left arm going up to his shoulder. It cuts to a closer angle after half a second and suddenly you see Lois lift her left arm up again to his cheek. Also Lex's thumb instantly changes position. (00:55:20)
Continuity mistake: Once Lois makes her presence known to Lex in his office, the camera pans over to show her standing in his double door leaning against the wall. In this shot, the left side of the door is closed and the right side open with her standing leaning against the right side door frame. But then it cuts to a close up of her and pans up, and now the left side of the door is what is open, and she is leaning against the closed right door. (00:54:00)
Continuity mistake: Just before Lois makes her presence known to him, Lex is shown in an overhead view in his office looking out the window. There is a desk to his right and his left a few feet away from him by the windows. It cuts to a side view of Lex's head and suddenly the desk to his right has vanished. (00:53:55)
Continuity mistake: When Dark Superman is digging the led ball out of his brain with some scissors, the lady with blue hair faints and falls over. After Superman gets up and walks past where they are, the lady is suddenly gone. It cuts to a view of Superman's feet as he walks, and suddenly the blue hair lady is there again on the ground with a black lady and a redhead suddenly appearing on the ground helping her. (00:53:45)
Continuity mistake: Once Dark Superman opens the salon door, the ladies inside all stop what they are doing and look at him in shock. The camera shows especially this one girl with blue hair working on the hair of a black girl and they face their left to see Superman come in. But once Superman starts walking in, suddenly they are much closer to him and they are facing the opposite direction as he passes by. Also the arm rest the black girl is sitting in suddenly disappears. (00:53:00)
Continuity mistake: As Dark Superman is walking down the street, he looks over and sees La Fantastique Salon which has a blue awning over its window. The awning having a pattern of blue alternating between light and blue. When he first sees it, the end of the awning by the door is the dark blue pattern. It then cuts to a different angle and suddenly the end is the light blue one. Also suddenly he is holding the paper in his hand higher, and the brick pattern on the wall changes slightly in relation to the door. (00:52:40)
Continuity mistake: When Lex is giving Dark Superman a list of Lex Corp competitors, there are two computer monitors shown on his desk. Then after Dark Superman is walking away in an over head shot, suddenly there is only one monitor. (00:52:10)
Continuity mistake: Lex holds up a piece of paper with a list of Lex Corp competitors to tell him to search for Superman's body. You can see the arm rest on the chair and him sitting in the chair. When Superman steps forward to take it, the angle changes and suddenly the drawing of Lex is off, appearing to be sitting on his arm rest. Also his fingers change in how he's holding the paper, and the position of his right arm and hand on the desk change positions. (00:52:00)
Continuity mistake: As Lex is telling Dark Superman that he is acting out of character, his desk is clear. Then while they are talking, a paper suddenly appears on his desk that he gives to Superman. (00:51:55)
Answer: In the comic book, Doomsday was put in a strait-jacket, strapped in metal bondage and placed in a cube like metal prison buried deep in the earth. It took him centuries just to break the bonds, then spent more centuries just punching his way out. With earthquakes, volcanoes and other natural disasters those events could shift Doomsday's prison to the surface.