So when king is moving (flying) Oda draw him without any detail to show us the effect of the speed, but what I notice is that in this form he doesnt have any flame coming from his back (hybrid). Did he use the flame as a jet engine to fly at very high speed?
Second I find interesting that the Editor's note say: What is that face...! Why do we need to care about this? Is it something like Katakuri or maybe something like Boa Hancock on her back (the slave mark). There is definitely a mark&tattoo behind King mask.
Last point where are currently Zoro&King? they look above the castle so they are some stages above the living flor where they started the fight.