Continuity mistake: After arriving back in Metropolis, Superman first tries to defeat Doomsday by simply blowing on him to freeze him. You can see that he is standing almost right next to the tank he just sat down when he is in the process of freezing Doomsday. But then once Doomsday has stopped moving and is frozen, the shot cuts to a different angle and suddenly he and Doomsday are much further away from the tank, and somehow trees behind Superman are half covered in ice as well. (00:18:20)
Continuity mistake: Once Doomsday is frozen, a shot from behind him shows a van behind him partly covered in ice from Superman's breath. The back side window is a full glass window. Then a little later after Doomsday breaks free and Superman pushes him back, suddenly the side window is a solid metal piece. Also the ice on the ground becomes thick snow suddenly and the van's door handle disappears. (00:18:30)
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 pushes Doomsday away once he breaks from the ice, Doomsday charges again, swinging a punch which Superman jumps aside to avoid. In that shot you can see the tank next to them and the .50 cal gun mounted on top of it. Then Superman retaliates and lands two hard punches on Doomsday and the camera cuts to a side angle, and suddenly the .50 cal has vanished off the tank. (00:18:40)
Continuity mistake: After Superman lands a couple punches on Doomsday, the creature grabs his fist and throws him down the street. As he hits the ground, you see a burning car behind him that is orange. The it cuts to a close up of Superman skidding and then getting up, the car behind him turns blue, and the damage to it changes. (00:18:45)
Revealing mistake: When Doomsday slams Superman down into a hummer, watch closely. You can see that Superman has no face or hair. (00:18:55)
Continuity mistake: Doomsday throws Superman at a building and he slams near a window, people looking out. It cuts to a close up as Superman falls to his knees and the people in the window suddenly change around. (00:19:05)
Revealing mistake: After Superman is thrown into a building, it cuts to Jimmy and Lois strapping themselves into a helicopter. The seatbelts in the chopper are not drawn correctly. The holes where they come out of the seat are not symmetrical, don't match from one seat to the next, and are overlapping the edges of the fabric on some and not on others. And then when it cuts to a side view of Lois, the holes are gone and it looks like the belt just stops at the seat. (00:19:10)
Continuity mistake: As Lois is starting up the helicopter with Jimmy, you can see the seats behind them and how they are designed, lots of lines and not plain, with the seat belts coming out about mid way down. But then as the helicopter is zooming by the camera, you can see now the seats are now plain looking, and the belts come out much higher up. (00:19:20)
Continuity mistake: After Lois and Jimmy get in a helicopter, the scene changes back to Doomsday and Superman fighting on a street. As Superman is attacking Doomsday, there is a yellow car in the street behind the creature. Superman then gets a few good hits off, and sends Doomsday flying backwards through the air. Suddenly the yellow car has turned into a large 18 wheeler truck. (00:19:40)
Continuity mistake: When Lois spots Doomsday and Superman from the helicopter, Jimmy is beside her holding his mouth trying to not throw up. His camera is around his neck and you can see the button to snap pictures is on the right side of the camera at the top. But them moments later when it cuts back to them, Jimmy is holding his camera to snap pictures and suddenly the button has vanished off the right side, and his finger is on the left side as if he is pushing the button there. (00:19:50)
Continuity mistake: From the air, Lois spots Superman and Doomsday fighting below, and points. It then cuts to Superman and Doomsday battling by some rubble. Cuts to a close up and then back again as Doomsday smashes Superman into the ground, and now the pile of rubble behind them has changed. (00:19:55)
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: Jimmy zooms his camera in on Doomsday as the creature spots him and begins climbing rubble to jump at their helicopter. As Doomsday is climbing up, it cuts to a shot from behind him and suddenly the rock and the way he is standing on it changes. (00:20:30)
Continuity mistake: After seeing Jimmy and Lois in their helicopter, Doomsday leaps through the air and grabs it. The window of the chopper cracks and the frame where he grabs it bends with his grip and his weight. But then as Superman grabs Doomsday, a shot from the outside of the chopper shows the window and frame fully intact, no damage. (00:20:40)
Continuity mistake: When Superman goes to set down the chopper that Jimmy and Lois are in after Doomsday trashes it, the air intake vent on the top of it is smaller than seen before. Then when he sets the chopper down and lets Jimmy and Lois out, the design of the intake vent changes completely. (00:20:45 - 00:21:20)
Continuity mistake: Jimmy kicks the side of the helicopter where Doomsday is holding on and Doomsday falls, but then grabs the chopper by the landing bars. His left hand is forward of the metal piece that holds the landing bar to the frame of the helicopter as he uses his right hand to grab into the side of the helicopter. But then after Superman pries Doomsday's right hand away and goes to cut through the connecting metal with his laser vision, Doomsday's left hand is suddenly holding on behind the connecting metal. (00:21:00)
Continuity mistake: When Superman pulls Doomsday off the chopper, there's a metal panel stuck to Doomsday's fingers and you see it still there as Superman throws him away. Then the angle changes just before Doomsday smashes through the roof of a building but suddenly the panel has vanished from his fingers. (00:21:10)
Continuity mistake: When Superman sets down the chopper, there is a building behind them with some people standing around. It cuts to a very brief shot of inside the chopper as Lois removes her seat belt and then cuts back to outside the chopper, and suddenly the people standing around have moved. Also the air intake on top of the chopper changes shape and goes from a lighter blue to darker blue. The damage to the windshield becomes more extensive between shots, the glass part on the bottom of the front of the chopper goes from being two parts to one solid part, and the broken landing leg changes from a light blue to being white like the body of the chopper. (00:21:25)
Continuity mistake: After Superman rescues the helicopter Lois and Jimmy are flying and sets it down, Lois reaches up and undoes the top half of her seat belt, and Jimmy is just sitting there in shock not touching his. It cuts to a different angle and Superman walks up. Lois suddenly has her full seat belt off, and Jimmy is helped out of the chopper by Superman, without ever taking his seat belt off. There was not a time laps between shots. (00:21:25)
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.