Sometimes Afrits (firedemons) get stuck in one specific frame of animation when they're killed. They remain in this state for several seconds. This seems to happen when they're very close to the ground at the moment of death. See screenshot in attachment

This bug also happened in the original game, I somehow think the doom's physics code isn't the most well written piece of code <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: --> .