These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Super Mario Bros 3
Best Level Ever: World 5-3. Goomba's Kuribo's Shoe. An entire generation of gamers can bond over how awesome that level was.
Although not quite as awesome as 5-3, 4-6 contains doors that change the size of the enemies between the giant size typical of world 4 and the standard sizes found elsewhere — kind of a 2D precursor to Tiny Huge Island from Super Mario 64.
The treasure ship, which shows up if your score and coins meet a certain criterion. When you go to it, it's kind of like a Doom Ship, except covered in hundreds of coins. It is glorious.
Demonic Spiders: Boss Bass, who can be found hanging around most of the stages in World 3, and has an annoying habit of swallowing Mario whole irrespective of what power-up you're using, instantly costing you a life.
Ensemble Darkhorse: The Koopalings went on to become an entire Darkhorse Ensemble.
However, the TRUE ensemble darkhorse is Kuribo's Shoe. Despite appearing in only one stage, of one level, of one game, it is enormously popular.
So much so that some fan-made hacks, such as Mario Adventure, made sure to let it carry over to every level.
Fan Nickname: Even though the DIC cartoon of this game has been dead for two decades, many fans still use "Doomship" to describe not just the airship levels, but the ships present in Super Mario Galaxy and other future Mario games.
The P-wing, which allows you to fly over any level (except 7-4 or World 8's fortress). Beat the game and you can restart it with twenty-eight in your inventory, enough to make the hard parts of the game a cakewalk.
Kuribo's Shoe is a possible subversion. The shoe is a game breaker in theory, but it's only found in one level, and that level would be easily clearable without it.
The Hammer Suit, as it allows you to kill most enemies that even fireballs can't kill (such as Thwomps, Podoboos, and even Bowser).
But it is rare, and one hit and it is gone. Also you can't slide down hills while wearing it.
On the other hand, crouching makes you immune to small fireballs, just like a Buzzy Beetle. (Bowser's fireballs still hurt you, though.)
It's possible to swim under the ships in world 8's navy level.
Running full speed ahead into the goal card always gives you a star card, three of which grant you a 5-up.
There are numerous places in World 7 (often allowing full-stage skipping), Bowser's Castle, and elsewhere where you can walk through a wall. See this video for a sampling.
Hilarious in Hindsight: The goombas are called kuribos in the Japanese versions of the series (hence Kuribo's Shoe). So the tiny ones in this game would be Little Kuribohs.
Nightmare Fuel: The music that plays when you read the letter from Bowser before World 8.
