Act 5, Sc. 2 lines 267-279: which lines notify the audience of an important bit of stagecraft needed to advance the plot?

And you, the judges, bear a wary eye.
Trumpets
HAMLET
Come on, sir.
LAERTES
Come, my lord.
CLAUDIUS
I’m not worried. I’ve seen both of you fence. But since Laertes is better, we’ve given him a handicap. He’s got to outdo you by three hits to win.
LAERTES
This sword’s too heavy. Show me another one.
HAMLET
I like this one. Are they all the same length?
OSRIC
Yes, my lord.
HAMLET and LAERTES get ready to fence.
CLAUDIUS
Put the goblets of wine on that table. If Hamlet makes the first or second hit, or gets back at Laertes by making the third hit, then let my soldiers give him a military salute. I’ll drink to Hamlet’s health, and into his goblet I’ll drop a pearl even more costly than those in the crowns of the last four Danish kings. Give me the goblets. And now let the drum and the trumpet play, and the trumpet signal the cannon outside to fire, and let the cannon tell the heavens, and the heavens tell all the earth that the king is drinking now to Hamlet’s health. Come on, let’s begin. Judges, pay close attention.
Trumpets play.
HAMLET
Come on, sir.
LAERTES
Come on, my lord.

HAMLET
One.
LAERTES
270No.
HAMLET
Judgment?
OSRIC
A hit, a very palpable hit.
LAERTES
Well, again.
CLAUDIUS
Stay, give me drink.—Hamlet, this pearl is thine.
275Here’s to thy health.
Drums, trumpets sound, shot goes off
CLAUDIUS drops pearl into cup
Give him the cup.
HAMLET
I’ll play this bout first. Set it by a while.
Come.
HAMLET and LAERTES play
  Another hit. What say you?
LAERTES
A touch, a touch, I do confess ’t.