Perhaps more like the moment the last sliver of hope that Sakura had disappears. I don't think she really believed Kariya when he hugged her and told her he would save her after what she had gone through almost immediately after being taken in, but deep down she might have hoped it could be true.
Of course we don't really know what Kariya actually said to her or how much Zouken told her what Kariya had done, we only got to see Kariya's final hallucination.
I did smirk at the quick flash of Kirei reveling in Rin's tears. It was only for a second, but he smiled at seeing her break down. It was also nice to find out that Kiritsugu didn't willingly abandon Ilya. He tried to get her back, so he could keep her safe. That just accelerated his death and hopelessness.