Ophelia: "Their perfume lost, take them back again..." The audience almost certainly won't've picked up the red bookmark in the book that Polonius forces Ophelia to take, then she gives to Hamlet accidentally with the "remembrances", and then Hamlet offers her the chance to reject her Red Cloth moment, but she takes it back and so effectively signs her own death warrant...

As I say, whoosh, totally over the audiences' heads, probably...