What hint is given in this scene that something tragic will happen act 1 scene 4 of Romeo and Juliet?

Romeo, Benvolio, and their friend Mercutio, all wearing masks, have gathered with a group of mask-wearing guests on their way to the Capulets’ feast. Still melancholy, Romeo wonders how they will get into the Capulets’ feast, since they are Montagues. When that concern is brushed aside, he states that he will not dance at the feast. Mercutio begins to gently mock Romeo, transforming all of Romeo’s statements about love into blatantly sexual metaphors. Romeo refuses to engage in this banter, explaining that in a dream he learned that going to the feast was a bad idea. Mercutio responds with a long speech about Queen Mab of the fairies, who visits people’s dreams. The speech begins as a flight of fancy, but Mercutio becomes almost entranced by it, and a bitter, fervent strain creeps in. Romeo steps in to stop the speech and calm Mercutio down. Mercutio admits that he has been talking of nothing, noting that dreams are but "the children of an idle brain" (1.4.97).

Benvolio refocuses their attention on actually getting to the feast. Romeo voices one last concern: he has a feeling that the night’s activities will set in motion the action of fate, resulting in untimely death. But, putting himself in the hands of "he who hath the steerage of my course," Romeo’s spirits rise, and he continues with his friends toward the feast (1.4.112).