Kagaya's illness had deteriorated his body to the point that his sclera was black. The anime however keeps them in their original white color. When Kagaya explains how he believes that human feelings are eternal, the visuals depict several of the glowing ball Hinaki and Nichika were playing with falling, possibly to symbolize the lives of those who died trying to defeat Muzan. In addition, when he remarks on how Muzan had rallied people against him in his cruelty, you Hashira (plus tanjiro even tho he’s not a Hashira) were running to the Ubuyashiki mansion in a hurry because they were under attack (Kibutsuji was there who’s the demon king) the destruction of the Ubuyashiki Mansion being blown up Mitsuri Kanroji, Love Hashira. Gyōmei Himejima, Stone Hashira. Muichirō Tokitō, Mist Hashira. Obanai Iguro, Snake Hashira. Giyū Tomioka, Water Hashira. Shinobu Kochō, Insect Hashira. Sanemi Shinazugawa, all got to the mansion late..they were too late