Super Mario Bros.
Super Mario Bros.
Mario Part 1 - Easter Egg Hunting
Mario Part 5 - Did You Know Gaming? Feat. MatPat from Game Theory
Zelda Part 2 - Did You Know Gaming? Feat. PeanutButterGamer
There's an invisible 1-Up in the first level of each world, but whether or not it appears depends on whether or not you collected all the coins in the previous world's 3rd level. For instance, in World 3-1, to make the invisible 1-up that's on the bridge appear, you need to collect all the coins in World 2-3.

There are only two exceptions to this rule: World 1-1 because it's the very first level in the game, and World 2-1 where you're allowed to miss 2 coins in World 1-3. However, the hidden 1-Ups will always appear if you use a Warp Zone or the level select trick after beating the game. Another caveat is that each hidden 1-Up will only appear once so if you make the hidden 1-Up appear and lose a life, it won't reappear.
Contributed by raidramon0
After losing all of your lives and returning to the title screen, holding A and then pressing Start will start you at the beginning of the last World you died on.
Contributed by MehDeletingLater
During a second playthrough Mario can obtain unlimited extra lives in World 1-2 through a glitch.
The player must start a 2 player game and Mario must die in World 1-2. As Luigi, the player must reach World 5-2 and die climbing the vine that comes out of a block next to a Hammer Bro.
When Mario re-starts World 1-2, the vine from World 5-2 will grow through the ground. Mario can can then climb the vine and come down between the Buzzy Beetles and earn 1-Ups.
Contributed by Kakariko Kid
The Mushroom sound effect is very similar to the flagpole music just sped up around 20 times its usual speed.
Contributed by Tuli0hWut
The Spiny eggs are thrown by Lakitu in a simple way, with no horizontal movement whatsoever. However, this is not the intended behavior; it's actually the result of a bug! The eggs are supposed to be thrown out relative to the player's speed, Lakitu's speed, the player's position, and a pseudo-random value, as well as bounce off of any blocks or walls that they hit on the way down.
Contributed by Soldier1337
The current world record for fastest time beating the game is 4:57.627 by speed runner darbian. This record beat out the previous record by less than a second.
Contributed by gamerofgames
Although Bloopers normally spawn only in water levels, they can be placed in non-water levels normally and will award a massive 1,000 points when stomped. Other "impossible" ways to kill enemies, such as hitting a Podoboo or Bowser with a Starman, only award the default 200 points. Given that Bloopers appear in non-water levels in the Japanese Super Mario Bros. 2 -- and also award 1,000 points -- this behavior was likely intended all along.
Contributed by DeerBoarDude
While a Goomba is the first enemy the player encounters, they were the last object added to Super Mario Bros. They were created after Miyamoto and his team decided that they needed an enemy that could be taken out with a single stomp, as opposed to the Koopa Troopas. Unfortunately, there was very little space left on the cartridge, and so it needed to be as small and simple as possible. They only used a single image, and made a walking animation by flipping it back and forth.
Contributed by CuriousUserX90
Super Mario Bros. was the first ever game to receive a movie adaptation, both animated and live-action. The first animated film was called Super Mario Bros.: Peach-Hime Kyushutsu Dai Sakusen! released in 1986 only in Japan. The first live-action film was the infamous Super Mario Bros. movie released in 1993.
Contributed by Mass Distraction
In the game's manual, it's stated that the Koopas turned the Mushroom People into stone, bricks, and plants. This could imply that throughout the game you're killing the inhabitants of the Mushroom Kingdom.
Contributed by ummwat
It's possible to access an additional 256 worlds in the game through a glitch. There are two methods to access them via the Japanese Famicom version:
• Having a copy of both Super Mario Bros. and Tennis, first insert the Mario cartridge and then remove the game at the title screen whilst it's still on. Then insert the Tennis cartridge, and during a match, remove the game and place Super Mario Bros. back in. Reset the console and at the title screen hold down A and press Start.
• The second method involves the Family Basic cartridge and the keyboard peripheral. By inputting a series of code and then swapping the cartridge with Super Mario Bros., reset the console and then hold down A and press Start, which will grant players access to one of the 256 glitch worlds.

The Tennis method can also be done with the western version of Super Mario Bros. but only on the NES-101 model.

Each of the worlds appear to reuse assets from the other levels, resulting in various bugged stages. The Tennis game method is possible presumably due to both it and Super Mario Bros. using the same addresses, but don't place the same check values. Leaving the power on also retains the RAM and the previous check value remains.
Contributed by KnowledgeBase
The Famicom Disk System version of Super Mario Bros. also contains World 0-1 but it is a full-fledged world with complete programming.

• 0-1 is a differently-textured version of 1-3, though it takes place underwater (even though there is no visible water and features bizarre elements, such as floating Princess Toadstools and floating, headless Bowsers).

• 0-2 is a carbon copy of 7-3.

• 0-3 is a copy of 4-4 that lacks its False Bowser and maze-like elements, features a different color palate (i.e. blue lava), and floating bloopers that can be stomped for 1000 points.

After beating 0-3, the player is taken back to the title screen (with the activation of hard mode upon starting the game), as if they had beaten the game.
Contributed by game4brains
The World 0-1, or Minus World glitch (in which Mario can visit a secret world before World 1, and entering the pipe at the end of it returns him to the beginning of the World), is fairly well known but there are actually two more worlds after it that can be accessed by hacking a flag pole into the level.

Level 0-2 is just another water level with a lot of unfinished level design and acts as one of Bowser's castles.

Level 0-3 is a land level with the flooring as a ceiling which you can break like normal blocks. This level also has enemies unlike 0-2 and ends just like a castle too.

Level 0-4 is a level that doesn't exist so the game just takes you to a black screen.
Contributed by TrevMaster3000
Using a glitch involving a Koopa Troopa, it is possible to jump over the flag at the end of any level and continue to walk on endlessly. In world 3-3 specifically, you can easily jump over the flagpole without the exploit.
Contributed by KnowledgeBase
If you encounter a Hammer Bro and wait for a while, it will eventually start chasing you down.
Contributed by Mario-Fan
Nobody knows exactly when the game was released in North America.
Contributed by beat_that_potato
Clouds and bushes use the same sprites, but alternate palettes.
Contributed by ummwat
The Bowsers in the castles of Worlds 1 through 7 are actually common enemies disguised as him. You can reveal the disguises by killing the False Bowser with fireballs.
Contributed by pyoro64
Super Mario Bros. was originally planned to be a shooting game. According to Shigeru Miyamoto, Mario's fireballs were going to be bullets, and he could fly on a cloud shooting at enemies.
Contributed by Silver964
In the game's manual, it says that the Koopas use black magic.
Contributed by nintendogamer199