Super Mario Bros./Codes

Minus World
By passing through a solid wall near the World 1-2 exit due to a glitch, it is possible to travel to "World -1", also known as the "Minus World" or "World Negative One" and considered by the game to be "World 36". This stage is identical to Worlds 2-2 and 7-2, but upon entering the warp pipe at the end, the player is taken back to the start of the level. Exploiting the same glitch in the Japanese Famicom Disk System is considerably different and has three levels, after which the player is returned to the title screen as though he or she completed the game. This glitch has been fixed in the Super Mario All-Stars remake as well as in Super Mario Bros. Deluxe. However, the glitch remains in the Animal Crossing version and the Wii's Virtual Console version. In Super Mario All-Stars, a player attempting to get to the Minus World will find that the pipes lead to Worlds 2, 3, or 4 as if the Warp Zone had been accessed in the usual manner. In Vs. Super Mario Bros. (the arcade cabinet version of Super Mario Bros.), the Minus World cannot be reached using the well-known method as the two bricks that allow the player to access the Minus World have been removed, though a different trick can be used to access a much smaller Minus World (consisting of the short underwater bonus area, looped infinitely). A reference to minus world can be seen in the "Underwhere" in Super Paper Mario when a Shayde says the Underwhere is also called "World -1".

Jumping over the flag
Dating from the time of the original Super Mario Bros. release, urban legend claimed that in levels 3-3 and 7-2 it is possible to jump over the flag at the end of the level by exploiting pulleys. The claim was for the most part unsubstantiated until 1999 when a NESticle movie demonstrating the capability was publicly released. When the engine was redone for the SNES game Super Mario All-Stars, this ability was retained while found less difficult to perform (and, interestingly, the -1 bug was removed). Creators of tool-assisted console videos have also demonstrated (in the original NES game) that the flagpole can be surmounted on several other levels including 1-1. This is done by exploiting a glitch to induce a Koopa Troopa to walk across the bottom edge of the screen and then using it for an extra bounce over the pole. However, jumping the flag is not very useful as the level goes on forever and is completely empty after this. There is nothing to do but to keep running forward until Mario dies from Time Over. There are also many levels in Super Mario Bros.: The Lost Levels in which jumping over the flag is possible.

Small Fire Mario
Accessed through a glitch, it is possible for Mario to obtain his Fire powers while remaining in a small state. First, Mario must get to Bowser in the fourth level of any world (excluding World 8) and be Super or Fiery. To activate the glitch, Mario must be positioned between Bowser and the axe. Then, Mario must touch Bowser (reverting him to his normal state) at the same time he collects the axe that destroys the bridge. A jump must be timed for both events to occur at once. If performed correctly, Mario will flash (as if he was hit) while the bridge is destroyed. Mario will also glide towards the Toad retainer as opposed to running towards him.

At this point, the glitch will have reversed what is considered "Small Mario" and "Super Mario". At the beginning of the next stage, Mario will start out as Super size, but one hit will make him lose a life (returning him to normal size upon death). Obtaining a Super Mushroom power-up will cause Mario to shrink to small size, while getting hit will cause him to grow back to his Super size. Obtaining a Fire Flower power-up will allow Mario to throw fireballs (and have his red/white color scheme), but still remain small and not able to break regular blocks. Also, the act of throwing a fireball will allow Mario to grow to Super size for only a split second before returning to normal size (most likely because a "Small Fire Mario throwing fireball" sprite was never created). The next time Mario loses a life, the glitch is "fixed" and the power-ups return to normal. This glitch has been fixed in the Super Mario All-Stars remake as well as in Super Mario Bros. Deluxe. However, it is present in the Animal Crossing and Virtual Console versions.

Performing the same trick as small Mario will result in another type of glitch. Mario will appear to die but will angle towards the Mushroom Retainer and off the bottom of the screen. The Mushroom Retainer thanks Mario as usual, and the game moves on to the next level.