Rainbow Course

A Rainbow Course is a special level found in New Super Mario Bros. 2. The music heard in rainbow Courses is a sparkly remix of the New Super Mario Bros. Wii Coin Heaven theme

A Rainbow Course can only be opened by finishing a level with the last two digits of the Time Limit both being the number of the world the player is on (World Mushroom being "7", World Flower "8", and World Star "9"), which is followed by the original Super Mario Bros. "Course Clear" theme playing, along with some fireworks going off and a rainbow appearing. Then, Mario can head to the beginning of the world, where a Rainbow World course has opened up. Flying Gold Blocks do not appear in Rainbow Courses, and players are also unable to use their inventory items.

At the beginning of every Rainbow World, Mario must enter a Cannon Pipe to be launched into a Coin Heaven-type area, which holds large amounts of coins, coin Roulette Blocks (including a larger one with a maximum number as 100 coins, instead of 50), 10 Gold Coins, and even a single 100 Gold Coin. Some courses have a Red Coin Ring that will gave the player a Gold Flower in their inventory if all Red Coins are collected. However, all Rainbow Worlds are slightly different from each other. If Mario falls off the course, he will not lose a life, but it will close up and Mario must redo the method of unlocking the Rainbow Course in order to access it again.

Trivia

 * All of the Rainbow Courses will automatically unlock when a player receives a SpotPass message from the game, regardless of what the message is about.