Pressing Select on the File Select screen will cause Mario to shrink and activate Easy Mode, indicated by those words appearing on-screen before selecting a file and just before a selected stage finishes loading. In Easy Mode, there are fewer enemies in levels, some mini-bosses such as Floating Faces take one hit to be defeated, and certain sections in Mario's Castle are less tricky to navigate.
In an interview, the game's director and designer Hiroji Kiyotake was asked about the characters and sprites looking different from other Mario games. He responded: "With Super Mario Land 2, one of our ideas was to not be bound by the conventions of the previous games. However, when we showed our first draft to everyone, they were like, “I don’t know… is this Mario?” We realized we were on the wrong path, so we toned down that idea and made something a little closer to the existing Mario world."
The Unibō enemies bear a striking resemblance to Gordo enemies from the Kirby series.
"HAPPY" is spelled out in stars in the first Space Zone level. However, it's too far up for the player to see it under normal gameplay. Jumping from a specific spot in the level will allow them to reach the letter 'Y'.
In the Pumpkin Zone, there's an enemy called J Son that walks like a Goomba but instead carries a hockey mask with a dagger stuck in it. This is a reference to the main antagonist of Friday The 13th, Jason Voorhees.
Totaka's Song can be heard if you get a Game Over and wait for about 2 to 3 minutes on the Game Over screen.
There is a glitch that's caused by going down a pipe, pausing the game, and exiting the level with Select. When Mario enters any level, he'll go through the floor as if he was still going down the pipe. Through this glitch, Mario will usually fall into a visual representation of the game's RAM. Blocks, pipes and other graphics are seemingly scattered randomly and can do random things, such as give Mario coins, hurt Mario, complete the level or crash the game entirely. It's even possible to trigger the credits in this area.