Here is my theory...
The eggs were being incubated (sorry if I suck at spelling today) by a hidden flame under the floor powered by a hidden generator. Now, the doctor did not want any Mimigas to escape, so he sent Misery (because the docter is a lazy shit) to overload the generator with a single lightning spell. This caused the generator to increase its heat production into dangerous levels. The eggs begun to crack, but the generator (I guess its more of a boiler, call it whatever you think) begun to backfire and overheat. The generator/boiler exploded and the explosions touch some really inconveniently placed fuel and other explosions. As soon as the two made contact...
...the entire Egg Corridor was engulfed in a wall of flames. (it's a wall because the game is 2-D) In addition to the generator/boiler keeping the eggs warm, it also powered all the electronics in the egg corridor. The earlier surge caused the computers to explode (due to electrical overload) thus igniting a more inconveniently placed stache of missle ammunition. This secondary explosion caused the roof to crumble and colapse. The heat caused the eggs to crack and any healthy dragon could have easily broken out of the egg shell, but the dragons did not make it... (kind of) The falling debris from the celing fell down and cracked the eggs open, thus freeing the dragon zombies. The dragon zombies caused even more cahos and destruction throughout the egg coridor, completely destroying anything in their path, and left hell in their wake.
All of these zombies were a failure. All except for one... Egg 00 was originally an experiment. Igor (while he was still alive) was originally testing to see if there was a different, safer way to hatch eggs. So he decided to raise one egg (egg 00) using human incubation methods. The experiment seemed to be succesful. He begun to make plans the replace the boiler method with the incubation method. Sadly, he would not be able to see the day to complete his project. One day he was really hungry. It was a bit of a walk to get back to the village, and he could not leave the eggs unattended. Suddenly there was a knock on the door. Igor opened the door to find a package. A package full of red flowers.
Igor had learned how dangerous the red flowers were, but he was so hungry. "What harm would there be in just a little taste" he thought to himself. He ate just one petal. He thought it was so delicious and unique, he ate more and more. After about eating half of the flowers, Igor begun to feel a bit warm. He thought he was just crazy, but he started to choke. He knelled on the ground, coughing violently, his eyes suddenly became bloodshot. He coughed up his own blood, and thats when he begun to transform into his enraged state. Being in this maddened state, he did not have the common sense to continue looking after the eggs. In his enraged state, he encountered and fought a robot, who was far to agile for Igor to keep up. After a series of bullets penitrating Igors flesh, Igor fell to the floor and reverted to his normal state, his rage finally quenched... his life finnaly ended... his dream however, was never accomplished...
But experiment 00 was successful...