Magic Doors (or magic doors) are special doors that appear only in World 4-6 of Super Mario Bros. 3 and its reissues in Super Mario All-Stars and Super Mario Advance 4: Super Mario Bros. 3. Upon the player entering one of the doors, the enemies and scenery (blocks and Warp Pipes) of Giant Land are replaced by their normal-sized counterparts. Likewise, entering a Magic Door when the normal-sized enemies and scenery are in effect reverts the level to its giant-sized form.
The two variations of World 4-6 also have a few minor differences in terms of Hidden Blocks and 1-Up Mushrooms. As such, players can explore different segments of the level in both sizes to find additional bonuses. However, the Magic Doors of the level are entirely optional and can be ignored if the player chooses to do so.
- Nintendo Power Volume 13, page 41.
- The Super Mario Advance 4: Super Mario Bros. 3 Player's Guide, page 60.
- Nintendo Power Volume 13, page 40.