The episode follows the series' protagonists, Phineas and Ferb, as they bulid an extremely large roller coaster starting in their backyard and going throughout the city.

When originally aired on August 17, 2007, "Rollercoaster" peaked high ratings in several categories, leading to the episode being the second highest-rated telecast Disney Channel received in its recorded history.

Phineas (Vincent Martella) and his stepbrother Ferb (Thomas Brodie-Sangster) are sitting lazily under a big tree in their backyard when they decide to construct a large roller coaster.

With their mother Linda (Caroline Rhea) at the grocery store, their sister Candace (Ashley Tisdale) wants to catch them in the act and "bust" them.

Candace goes to the store to tell their Mom of the boys' activity, though she is keen on neglecting it, while their neighbor and best friend Isabella (Alyson Stoner) goes up to Phineas and asks "Whatcha doin'?".

Meanwhile, Phineas and Ferb's pet platypus Perry (Dee Bradley Baker) performs his act as a "secret agent" codenamed Agent P, being informed by his short-tempered boss Major Francis Monogram (Jeff "Swampy" Marsh) that his arch-nemesis, an evil but silly scientist named Dr. Heinz Doofenshmirtz (Dan Povenmire), has bought 80% of the Tri-State Area's tin foil.

However, Doofenshmirtz soon learns that his plan is flawed because the magnet has only taken the tin foil off the eastern seaboard, forming it into a 2-ton giant ball.

[4] Similar to Povenmire, Marsh spent his summers exploring and taking part in several different activities in order to have fun.

[3] Vincent Martella, Thomas Sangster, and Ashley Tisdale, who voice Phineas, Ferb, and Candace respectively, were all hired by the casting department because of their popularity within the target age-group and general belief in their ability to perform their roles.

Disney Channel wanted to start off the series in a special way, though they did not use "Rollercoaster"; instead, they chose the episode "Flop Starz", and aired it in a worldwide premiere.

[15] These high ratings lead to the episode being the second highest-rated telecast Disney Channel received in its recorded history.

[16] The events of "Rollercoaster" would be revisited in the season 2 episode "Phineas and Ferb's Quantum Boogaloo", which sees a future adult version of Candace returning to the events of the episode in a time machine to help her present counterpart successfully bust Phineas and Ferb for the rollercoaster.