If you let a Chain Chomp tug on its chain 49 times, it will actually break free.

The Koopalings were based on seven of the game's developers. They were all later named after musicians by the American localization team, as no distinct names were given in the Japanese version. It's also speculated the musical names were chosen because their scepters resemble microphones.

It was once planned for Mario to have a power up that turned him into a Centaur. This isn't as outlandish as it seems; the Tanooki suit was also inspired by the legendary Tanuki.

The box art for the game shows images from earlier stages of the game's development. The image of word 1 has different paths when compared to the final version, and the second image doesn't represent anything seen in the game's final build.

A popular long-standing fan theory about Super Mario Bros. 3 was that it was actually an elaborate stage play.

The commonly cited evidence that supports this theory include:
•The game's title screen starts with the rise of curtains, and the game ends with the fall of curtains, as well as curtain calls for each World and several characters during the end credits
•Some platforms are hanging down from the "sky" by wires implying it's scenery being hung from the ceiling
•Some platforms are bolted to the wall and cast shadows against the "sky" suggesting it's a backdrop
•If Mario/Luigi kneels on white block platforms for six seconds, he will fall behind them and can walk behind the scenery
•Some platforms are sticking out through carved-out slots in the backdrop suggesting they are being controlled by hidden machines behind the set
•Each regular stage ends by exiting stage left and going "backstage" into the dark goal area
•Every injury or death in a stage is Mario/Luigi messing up the scene (the "Mario was never once in any real danger" part in the attached image is not necessarily true as unintended injuries and deaths can happen in theatre)

One overlooked piece of circumstantial evidence that supports this theory concerns the fact that the Kings of each World that are transformed into different creatures by the Koopalings are never actually seen being transformed into creatures, or transforming back into humans after Mario defeats a Koopaling. The way every Koopaling defeat plays out shows Mario falling from the airship holding the King's magic wand, the scene fades to black, and then the lights come back up inside the castle showing the King already transformed back into a human before either the wand or Mario return to the castle. This suggests that the Kings were never transformed in the first place, because they were all actors waiting to get into place for their scenes, and the transformations are the suspension of disbelief. It should be noted that the Game Boy Advance version of the game partially discredits this by adding cutscenes showing each King being turned into creatures by the Koopalings, but they are still are not seen being transformed back into humans.

In a Q&A interview to promote the release of Super Mario Maker in 2015, Shigeru Miyamoto confirmed the theory, that the game was all a performance.

The island with the castle in World 3 resembles Japan, with the castle being the location of Kyoto, Nintendo's headquarters.

The fortress in World 1 was slightly changed from the Japanese version to make things a bit easier. The right wall in the spike hallway was originally farther away, and the door was under a spike.

Several of the Koopa Kids' names are parodies of various musical celebrities, most of whom were popular at the time of SMB3's production.

- Iggy Koopa is named after American rock singer Iggy Pop.
- Lemmy Koopa takes his name from Lemmy Kilmister, a British heavy metal artist best known from his work in the band Motörhead.
- Ludwig Von Koopa is named after 19th Century composer Ludwig van Beethoven, and shares his wild hairstyle.
- Morton Koopa Jr. is named after American pop and country singer Morton Downey Jr., now perhaps best known for his self-titled talk show. Morton Koopa Jr. also has a white face with a black star over his left eye, the trademark makeup of guitarist Paul Stanley from KISS.
- Roy Koopa is named after Roy Orbison, and both wear horn-rimmed sunglasses.
- Wendy O. Koopa is named after Wendy O. Williams, an American punk singer.

It's unclear who Larry Koopa is supposed to be based on, but he could be based on Larry Mullen Jr, the drummer for the band U2.

For every 80,000 points you score, a matching card game will appear on the board. This is a chance to receive items such as coins and power-ups. There are only a total of Eight (8) different patterns.

The Water Land theme was later used as the theme for the Fairy Fountain in the Legend of Zelda series.

The sound of the warp whistle which is based on the recorder from the original Legend of Zelda, can be heard in the title screen theme of The Legend of Zelda: Ocarina of Time.

The three islands on World 7 (Pipe Land) are actually shaped like the Overworld Pipe sprites.

id software sent a PC demo of Super Mario Bros. 3 to Nintendo hoping to gain authorization to make an official port. Nintendo was impressed but declined, deciding to stick to their own platforms. The demo was based on a test they named 'Dangerous Dave in "Copyright Infringement"', which was a playable recreation of World 1-1 with Mario's sprite replaced by John Romero's Dangerous Dave character.

Before the US release of the game, gameplay footage appeared in the movie "The Wizard." This served as an advertisement for the game and helped ensure its commercial success.

The power-up "Kuribo's Shoe" is actually the Japanese name for the power-up, but it was left unchanged for the English release. Kuribo is the Japanese name for Goomba.

Many changes were made when porting the game to the Game Boy Advance. The changes were made in order to make the game easier, and to accommodate for the system's smaller screen resolution. These changes include adding coins and power-ups, making jumps shorter and easier, and moving platforms so they could fit on the screen.

The Nintendo Entertainment System version of the game was released twice in English, and the worlds were renamed in the second version.

Desert Hill was changed to Desert World.
Ocean Side was changed to Water Land.
Big Island was changed to Giant Land.
The Sky was changed to Sky Land.
Iced Land was changed to Ice Land.
Pipe Maze was changed to Pipe Land.
Castle of Koopa was changed to Dark Land.

Grass Land kept its name.

As seen in early screenshots, Koopa Troopas and Hammer Bros. were going to host two mini-games. The minigames were a Question Block and a Dice Block game respectively, which also would have marked the first Mario game to have the Koopas standing instead of on all fours. These mini-games and their hosts seem to have been replaced by Toad.

This game was the first appearance of the common Mario enemy Boos. They were actually based off of game designer Takashi Tezuka's wife, who would normally shy away from people, but had an explosive temper, triggered by the high amount of time Tezuka was spending at work.

The western version was slightly different compared to the Japanese release. The game was a bit easier, some levels and object placements were slightly altered, the speed of the credits was faster, as well as some other minor details.