List of New Super Mario Bros. U pre-release and unused content

These are the beta elements of New Super Mario Bros. U.

Early Ideas
Miis were originally going to be playable in all modes, but Story Mode does not support Miis.

Boost Mode was originally known as Assist Mode or Assist Play, as seen in a perspective image below. In early builds, it worked similarly to the final version, except that Blue, Purple, Red, and Green Boost Blocks kept their symbols at all times, and didn't spit out coins. Instead, a separate Boost Block did that, a smaller one with a coin symbol. These types of Boost Blocks would only appear if the Wii U GamePad player tapped on the screen twice. The amount of coins that were given were less than the final version. Instead of five, it would have given three instead. Boost Mode also seemed to lack the Boost Star and special Boost Mode properties.

Boost Rush Mode has not changed a lot from the earlier builds, except that the Coin Meter was below the Coin counter instead of the timer.

Like in New Super Mario Bros. Wii, at one point, the game developers were actually going to make Princess Peach a playable character, like in Super Mario Bros. 2, but they eventually decided against this because of how difficult for them to animate her dress. Another reason against the option to play as Peach is because of the fact that such would obviously defeat the purpose of her as the "damsel in distress."

Early Builds
As shown by the screenshots below, the HUD of the game was originally more like New Super Mario Bros. Wii's, with white, stylized font for everything besides the Coin counter, which had orange instead of white. Later on, the HUD font was changed to a more opaque and metallic font.

In New Super Mario Bros. U first builds, Warp Pipes had a brighter and more plastic-like look, similar to its predecessors. In the final version, they're darker having a more metallic look.

In early builds of New Super Mario Bros. U, the Acorn Plains map looks substantially different. The map was significantly less detailed, the Acorn Trees did not show the Super Acorns, the mushrooms that leaded to Mushroom Heights were just red, the map had two red Toad Houses, and the green Toad House was in a different spot, there are two Enemy Courses instead of one, and the spot where the Balloon Baby Yoshi was, is gone, implying that Baby Yoshis could not be taken into any course, or that the option was not programmed yet. A bridge also extends from the level which Yoshi Hill will later become, implying that Yoshi Hill (or the course that was there in the first place) would have had a secret exit that skips Mushroom Heights and Rise of the Piranha Plants entirely.

Trailer
The version of Painted Swampland shown in the E3 2012 trailer had pipes that were primarily green, while the final version has pipes of varying colors. Another course presented in the trailer was shown an Acorn Plains course with Bubble Baby Yoshi, tilting mushrooms, and Hammer Bros. This course could've been an early version of the Rise of the Piranha Plants course, but otherwise, the course is not present in the final game.

Demo
Acorn Plains Way, Mushroom Heights, and Spinning Star Sky were named Course 1, Course 2, and Course 3 respectively in early E3 builds, presumably to avoid spoiling the world/names.

Acorn Plains Way has gone through various changes since the original showing during June 2012's Nintendo Direct, mostly in the main grassy area. Most noticeably is that the pipe leading to the sky sub-level has been moved further back in the final build and the hidden area near the Midway Point was much more narrow and shorter in the E3 build.

Baby Yoshis in E3 builds did not vocalize the chorus at all. Later builds had Balloon Baby Yoshis vocalize the chorus, though the other Baby Yoshis remained silent. Glowing Baby Yoshi in the E3 2012 trailer had the ability to glow brighter when the player shakes the Wii Remote, though a sound effect did not accompany it. Balloon and Bubble Baby Yoshis do not come out of eggs in Question Blocks, unlike in the E3 demo, and are only found in the main map.

The Peach's Castle seen in Acorn Plains Way had its colors more faded out in early E3 builds.

Early Enemies
Originally, Deep Cheeps were going to appear in the game, but in the final game they do not appear anywhere in the game. Artwork of a Deep Cheep was made for the game. The absence of them could possibly be that they have similar behaviors to Spiny Cheep-Cheep.