The person hiding in the mirror was Illuso from the Hitman Team. Fugo ends up being dragged into the mirror by Illuso's Stand, Mirrorman. Fugo then summons his own Stand, Purple Smoke. Despite Giorno wanting to find Fugo, Abbacchio decides to go look for the key, since that was their mission. However, once Abbacchio finds the key, he also gets dragged into the mirror world...
And yet Giorno... That stupid brat...
...ومع ذلك جورنو... ذاك الطفل الغبيّ
Aber Giorno hat das versaut.
Die hohle Nuss.
Pero el estúpido de Giorno…
Pero el estúpido de Giorno…
Giorno ! Tu fous quoi ?
E invece Giorno... Quel cazzo di moccioso...
E mesmo assim, esse panaca do Giorno...
Зачем, Джорно? 
Что ты наделал, сопляк?!