These notes are from the description of ヴァーサタイル's 28:44 run, as translated by me.

How to use knockback from explosions

When you take damage from an enemy, the knockback direction is stored, and is reused when you blow yourself up with the Balloon Bomber or the Mines.

It is stored even when you transition between worlds/areas.

Also, the knockback direction is determined by whether the right half or the left half of your body is hit. The direction you face does not affect it.

How to do ladder clips

Press the down button immediately after very briefly pressing the up button. (Also possible by pressing up and down simultaneously on 1P and a 3P's Joycard¹.)

When you try to climb a ladder from a position slightly to the side, you will automatically shift horizontally to align with it and climb it.

But when you press the down button while this automatic horizontal shift is happening, you will pass through the block under the ladder.

It's easy to fail if you hold the up button for a long time, so make this input as short as possible.

The closer you stand to the ladder, the shorter the time window becomes.

If you fail, you will remain stuck in the block, and the screen will vibrate.

In case you can't get out by jumping or boosting from an explosion, escape with the Angel Ring.

(There are rare situations which you can't escape with the Ring, in which case, you're stuck.)

How to do the double pickup bug

The moment a coin or quiver spawns (is displayed) after you defeat an enemy, be sure to touch it with both your body and sword at the same time. (4F window)

It is also possible to get a double pickup when a coin has already appeared. (2F? window with a jump attack; 1F? window with a walking attack.)

¹ A Joycard is a common brand of 3rd-party Famicom controller. Since the original Famicom had two controllers hard-wired to the console, extra controllers would have been plugged into the 15-pin expansion port on the Famicom, effectively acting as a third controller.