Jane Foster: Like an Einstein-Rosen Bridge?
Thor: More like a Rainbow Bridge.
Many cultures have different connotations on what a rainbow is, having made their theories long before science revealed it to just be reflection, refraction and dispersion of light in water droplets. One common idea is that this arch of color is used as a vehicle for otherworldly beings.
This form of Not Quite Flight can be read in a number of ways. Maybe they are Sky Surfing, treating the front-end of a rainbow as a surf-board surfing across the ocean of clouds. Perhaps the rest of the rainbow is a vapor trail that refracts the many colors through the air. Maybe rainbows are giant snakes that eat elephants and people and the user is just their owner, the snake their mighty steed.
- Certain cards in Yu-Gi-Oh! create rainbow-like bridges for monsters on the field to use, like Rainbow Blessing and Rainbow Bridge Bifrost.
- Fantasia: After the storm in "Pastoral Symphony", the goddess Iris flies by, leaving a rainbow behind her. Cherubs and baby pegasi play around the rainbow and slide down it.
- In Little Angels: The Brightest Christmas, the angels travel by turning themselves into a rainbow, each of them acting as a separate stripe.
- In the Marvel Cinematic Universe, the Bifrost is a dimensional energy harnessed by the Asgardian people through a crystalline, prismatic "rainbow bridge" that Asgardians use as a means of traveling across the universe. It is harnessed and controlled through Heimdall's Observatory, Heimdall himself being capable of using this power in short intervals, such as when he sent the Hulk back to Earth after Thanos defeats him in Avengers: Infinity War. Should the bifrost be left open for too long, the energy becomes destructive and is capable of destroying planets, as is what almost happened to Jotunheim in Thor.
- In Centaur Aisle, one of the early Xanth books, the party uses a spell to ride a rainbow for rapid travel from the southern tip of Xanth up to the northern Mundane border.
- In Sweet Story, it is revealed that rainbows are used by rainbow pirates as transportation, allowing them to plunder wherever the rainbows lead and leave along with it. Considering Sally's wish made it impossible for it to ever rain water again, this link between worlds is severed forever.
- Several Land of Oz books have a minor character named Polychrome the Rainbow's Daughter, a sort-of sky fairy who comes down to Earth on a rainbow, and needs the rainbow to return for her in order to get back up to the sky.
- Iris from Classical Mythology was a goddess that acted as a personal messenger of Hera, rainbows being her iconic method of transportation between Earth and the Heavens. She has a sister named Arke who performed a similar role for the Titans during their war with the gods, who represented the secondary faded rainbow sometimes seen in the shadow of the more prominent one.
- The Trope Codifier here is probably from Norse Mythology, where Bifrost was the name of the rainbow bridge that connected Asgard (home of the gods) to Midgard (home of humans). The Midgard end could be moved around, but the Asgard end always connected to Heimdall's home of Himinbjörg. Like everything else in Norse Mythology it's destined to be destroyed in Ragnarok when the forces of Muspelheim storm the bridge to get to Asgard.
- Every (non-cutscene) appearance Bianca from Spyro: Year of the Dragon makes to Spyro directly has her appearing when a rainbow weaves its way through the environment before landing in-front of him, Bianca appearing from where it landed. Taken Up to Eleven in Spyro Reignited Trilogy with the inclusion of Fantastic Fireworks.
- Every game in the Mario Kart series features Rainbow Road as its final track, in which the racers drive on a rainbow floating in space (or in one case, above a city).
- In the Strong Bad Email "flashback", Strong Bad's (probably) made-up tale of how he met Homestar involves him and Coach Z riding down to Earth from the moon on a rainbow bridge.
- In The Order of the Stick, there's a rainbow bridge that connects Valhalla and the plane where Durkon meets with the gods.
- The Wings of Tinabi from Xiaolin Showdown is a Shen Gong Wu that sprouts wings, bestowing its user the power of flight, leaving behind a rainbow trail in the process.
- The titular Rainbow Brite uses rainbow pathways to travel places, mainly between Earth and Rainbowland.
- Giant Realistic Flying Tiger from Uncle Grandpa leaves a rainbow-colored trail behind her, which is implied to be, um... coming from her butt.
- In the SpongeBob SquarePants episode "Life of Crime", Patrick needs money, so SpongeBob takes him to "The First National Bank of SpongeBob" by sliding down a rainbow to the pot of gold at the end (which, unfortunately, is empty).