if a ghast or blaze fires fireballs at you and you quit and reload the world, the fireballs will slow down and eventually stay in place

the bug is on the summary. the only way to get rid of them is to set the difficulty to peaceful. you can also get rid of the ghast fireballs by reflecting them. this glitch makes ghast fireballs a "weapon" that you can shoot at enemies, but this can only be done legitimantly in the nether.