C377 Firework Tactics

Generally speaking,

"Pork Serum" was installed on the arrowhead, so there was no need to open the cap.

So...

Why did Ma Wuti and the others open the bottle cap?

This was because of the requirement of the "Technique of Firework."

After the bottle cap was opened and the arrow was shot out, the "Pork Potion" inside the bottle would leave behind along the bottle's opening