suppermariobroth:

In the Forest Fortress in Super Mario World, it is possible to defeat a Grinder by sliding into it using the Triangular Block. Since Grinders are not supposed to be defeated, its sprite becomes glitched as it falls offscreen. (Footage recorded by me from a SNES emulator.)

suppermariobroth:

In Super Mario World, taking a Buzzy Beetle through the exit pipe in Donut Plains 2 results in the Buzzy Beetle’s shell assuming a grey color scheme. In addition, no matter how much time passes,
the Buzzy Beetle will never emerge from its shell again. (Footage recorded by me from a SNES emulator.)

suppermariobroth:

In Super Mario World, jumping on the platforms in Vanilla Ghost House in the order shown will produce a hidden 1-Up. The reason is that four of the platforms contain special control points that, if touched in order, will generate a 1-Up when Mario touches the last one.