Rainbow Road



Rainbow Road is the final course of the Special Cup featured in all Mario Kart games and serves as the ultimate race in terms of difficulty in order to win the definitive trophy of each game it appears. As their names suggest, these courses are made of rainbow-colored glass or metallic surfaces that are either one color or change their color as racers drive on them, depending on the game they appear in. Most of these tracks are transparent throughout the Mario Kart series. They typically appear floating in deep space or the Earth's atmosphere, although the one in Mario Kart: Double Dash!! and the remade and  in Mario Kart 8 hang suspended in a starry night sky above a landscape. Most appearances of this course contain few or no railings, putting racers at risk of falling into space, and each Rainbow Road also contains its unique hazards. Due to these obstacles, Rainbow Road is among the most difficult courses in each Mario Kart game. Starting in Mario Kart 7, some of the Rainbow Road courses have sections of the race track that are not rainbow-colored. Rainbow Road is also usually a long course when compared to other courses. Rainbow Road has also made some appearances in other games outside of the Mario Kart series, as well as in The Super Mario Bros. Movie.

Mario Kart series
Rainbow Road has appeared as multiple incarnations throughout the Mario Kart series:

Mario Hoops 3-on-3


Rainbow Road is the unlockable third dribble race from the "challenges" section in the basketball game Mario Hoops 3-on-3. However, this Rainbow Road floats above the clouds and around a clock tower, and not much of the course is fully seen when playing.

Super Mario Galaxy 2
In Super Mario Galaxy 2, Rainbow Road appears in both missions of the Rolling Coaster Galaxy, but it is very different than in its previous appearances. While it does retain its appearance, it is curved and appears to be made up of rainbow tiles instead of the colors simply being contiguous, much like the Rainbow Road from Super Mario Kart in which the track was also made up of rainbow tiles. Instead of just the Rainbow itself, it also has several platforms shaped both like mushrooms and squares with different colors. Despite taking place in space, this Rainbow Road features a cloudy sky as a background. Along the way, Mario or Luigi must avoid several obstacles like towers and Bob-ombs. Also, the two brothers can earn two Power Stars for finishing the course, one for the normal mission, and another for collecting 100 of the 110 Purple Coins. The music played when riding on Rainbow Road is a remix of the music played on the The Princess's Secret Slide in Super Mario 64.

Super Smash Bros. for Nintendo 3DS
Rainbow Road appears as a stage for Super Smash Bros. for Nintendo 3DS, taking the appearance of its Mario Kart 7 incarnation. Like Port Town Aero Dive from Super Smash Bros. Brawl, it is a cruise-type stage where players fight on a platform that flies around the course, which also occasionally lands on the course itself. While on the ground, Shy Guys can drive by and damage any fighters in its way, like in the Mario Circuit stage from the previous game.

A Rainbow Road (with the racers driving karts from Mario Kart 8) also appears in Rosalina's announcement trailer, where Mario, Luigi, Peach, Bowser, and Donkey Kong are all racing each other only to be suddenly interrupted by Kirby on his Warp Star, followed by Rosalina and a Luma. This Rainbow Road does not appear in-game, though, but it takes a slight resemblance to the DS rendition.

Paper Mario: Color Splash
Rainbow Road plays an important role in Paper Mario: Color Splash, as it leads directly to Black Bowser's Castle. The road is formed after all six Big Paint Stars are retrieved. Luigi drives Mario and Huey over to Black Bowser's Castle via his kart as the road is too slippery to walk on. Eventually, all but Huey (who elects to stay behind to ensure the black paint does not seep into the ocean when Black Bowser's Castle falls down) escape the castle and return to the road. While comforting Mario about Huey's decision, Luigi indicates that he knows Huey will probably be back as promised as the former has "fallen off Rainbow Road more times than [he] can count."

The Super Mario Bros. Movie
Rainbow Road appears as a location in The Super Mario Bros. Movie, leading towards Bowser's Castle. After Mario, Princess Peach and Toad convince Cranky Kong to recruit the Great Kong Army for a raid on Bowser and his army, the heroes speed off a ramp on karts in the Jungle Kingdom that lands them on Rainbow Road. The Koopa General warns Bowser of the impeding planned raid, prompting Bowser to order an ambush on the heroes. Koopas on karts ambush the heroes on their drive down Rainbow Road, prompting an immense battle between the two forces. The Kongs are captured by the Koopas, while the Koopa General becomes a Blue Shell and strikes Donkey Kong and Mario causing an explosion that sends them spiraling down into the ocean below them. Meanwhile, Peach and Toad manage to escape the attack and retreat to the Mushroom Kingdom.

As a reference to the games, there is a scene where Mario hops from one segment of the road to another directly below, a possible reference to the famous Mario Kart 64 Rainbow Road shortcut. Additionally, when the characters jump off a large ramp and land on the road, a rendition of the music for Rainbow Road from Super Mario Kart briefly plays.

Super Mario RPG (Nintendo Switch)
Rainbow Road is shown in the Nintendo Direct trailer for the Switch remake of Super Mario RPG. It is unknown what role it plays in the game.

Trivia
Pista Arcobaleno Regenbogen-Boulevard
 * Starting with Mario Kart: Double Dash!!, the surface on each Rainbow Road (including the retro ones in Mario Kart 7, Mario Kart 8, Mario Kart 8 Deluxe, and Mario Kart Tour) creates a unique metallic sound when racers drift, hop, or perform a sharp turn on them.
 * F-Zero GX also has a track similar to Rainbow Road called Phantom Road, that does not take place in a starry night sky or the deep space like most Rainbow Roads, but rather in a psychedelic cybernetic void. In addition, the track has only one color that constantly shifts through the color spectrum as opposed to having the traditional rainbow-looking appearance. Earlier builds of the track that remain in F-Zero AX retain the Rainbow Road moniker, most likely as a nod to its predecessor.