Mario tries to make the cave people's lives better by inventing the wheel for them, which leads to cars and way too many traffic problems. The now angry cave people kick the Mario Brothers out of the city just before King Koopa launches an attack.
Kootie Pie steals Dome City's Mama Fireplant to keep her warm in her Ice palace. Mario and company race to retrieve the fireplant before the residents of Dome City freeze.
Mario and company visit King Koopa's circus, where they discover the audience is going to become some hungry dinosaurs' next meal.
Mario, Luigi and the Princess are captured by a Koopa Wizard named Wizenheimer while in the Enchanted Forest. It's up to Yoshi and Oogtar to enter his haunted house to save them.
King Koopa goes into the fast food business and his food is a hit with everyone in Dome City, except for the Princess. But no one knows that Koopa sneaked in a side effect for those who eat his Egg Scoopa Koopa sandwiches, turning them into Chickadactyls. Only Mario and the Princess remain unchanged, so it's up to them to stop Koopa.
After Mario and Luigi yell at him, Yoshi runs away. He then meets the Dino Riders, who accept him into their gang, and are planning to capture the Mario Brothers to get gold coins from King Koopa.
Mario re-invents the telephone for the cave people. He soon regrets it, however, when he and Luigi have to keep protecting the cave people, who are spending all their time talking on the phone.
Luigi teaches the cave people about farming and growing their own food before the coming winter. But when the crops are stolen by Cheatsy and his Gophers, it's up to Mario, Luigi and Yoshi to get them back.
King Koopa makes Rock TVs to distract the residents of Dome City, and to brainwash the cave people to storm the Dome Castle to capture Mario and Luigi.
During a football game with the cave people, Luigi gets turned into an egg by a Koopa Wizard. When Bully and Cheatsy take him back to Neon Castle, Mario and Yoshi have to play a football game against the Koopalings to get him back.
Mario brings Christmas to Dome City to encourage the cave people to act nicer toward each other. When Oogtar tries to get his hands on the best presents, though, he winds up getting taken by the present-stealing King Koopa. It's up to Mario to save Cave Christmas for Dome City.
When Hip and Hop see the school in Dome City, they insist they should enroll. Although King Koopa refuses to let them, they become students anyway. When Princess Toadstool tells Yoshi and Oogtar to show the Koopas around, they quickly become enemies.
At Yoshi's bedtime, Luigi retells the story of their first adventure together in Dinosaur Land, and how Mario, Luigi, and Princess Toadstool met Yoshi.
The opening title sequence
An animatic for the Super Mario World opening title sequence
