Bowser's Mushroom Factory is the first episode of the first season.
Bowser had once again captured the princess. But suddenly, Mario and Luigi arrived to rescue her. After Mario stomped on Bowser to put him out of commission, they helped Peach out of the cage and left.
When Bowser awoke a little while later, and noticed that Peach was missing from the cage, he was enraged. His two minions, Goombas and Koopa came to him. Bowser was looking up at Mario, who got bigger by eating a Mushroom. This gave him an idea, and he sent his minions to build him a building that would give him Mushrooms. When it was complete, his minions blindfolded him and led him to the entrance, where they took off the blindfold. A sign above the entrance of the building read "BOWSER'S MUSHROOM FACTORY."
Bowser was amazed at his minions' work. He was even more amazed when they led him into the factory, past a security light, and up to a conveyor belt. Koopa demonstrated by pressing a button next to the belt. Soon, a Mushroom came, and Koopa gave it to Bowser, who greedily ate it. However, Bowser didn't grow, which caused him to be enraged and leave the factory.
At Mario's house, Mario was going through his mail. He set aside two bills, then found a letter from Peach. It read, "Dear Mario, Please come to the castle. I've baked a cake for you. Yours truly, Princess Toadstool (Peach)." Excited, Mario called Luigi. However, he was busy writing in his diary. When Mario called him again, Luigi hastily finished his entry and came to Mario, who showed him the letter. Luigi accepted, and the two set off for the castle.
On the way, Mario noticed a sign directing to Bowser's Mushroom Factory. Mario wanted to go there, but Luigi knew not to. After some convincing from Mario, they finally entered.
Mario and Luigi stopped at the security light when the light turned on. Goomba arrived, saw the Mario Bros, and jumped into a warp pipe which was near the conveyor belt. Koopas saw the Mario Bros. coming, and ran over to the nearby phone to contact Bowser.
Meanwhile, Bowser is seen flossing his fang, suddenly his phone rings. It was Koopa, informing him of the Mario Bros.' presence. Enraged, he got into his car and drove off.
Mario got a mushroom and did grow, but Luigi had his mushroom being eaten by Goomba. Peach went on Yoshi to see what the Mario Brothers were doing. Luigi saw that Mario has shrunk, and they go and let Luigi get a mushroom. And so he did. However, the mushroom factory was collapsing, causing Bowser to be covered in pillows dead. When Mario finally went to the castle, the cupcake is gone. It is revealed Toad ate it and the episode ends.
- The conveyor belt is made of K'nex.
- It is very coincidental that this episode was posted on 10/10/10, and its length is 10:10.