Where are these followers later? Where did they go? How did Ophelia lose them? And how did Gertrude come to be following her instead? And why would a Queen be out in the countryside watching a young girl drown herself? Especially if the king has appointed some guys to follow her close. Theoretically they are following her to prevent her from doing exactly what she does. How does a young woman in dire emotional straits shake off trained followers? Or does this following cease? Once Laertes shows up – maybe Claudius calls off the Ophelia suicide watch. Which is, of course, a mistake.
It is interesting how no one in the scene ever questions how Gertrude knows all the poetic description of Ophelia’s death. It’s kind of a beautiful mystery. And the sort of thing, if this play were written today, some dramaturg would insist that Shakespeare put a line in about it. Or cut the speech – because it raises questions that aren’t answered.