Suitable flesh plot hole? [spoilers]

Help me to understand because I cannot find anything on Google. After derby runs over asa waite multiple times and he is on the operating table, he just randomly starts chanting the possession when he is nowhere near Elizabeth and somehow it works. Every other instance of it he has to be in the person's ear, or within earshot for them to hear it. But somehow this one works? Seems like a major plot hole and pretty weak way to end the movie as a whole.