You can push a block through the worldborder with a sticky piston. But the block moves through the worldborder. After that there is no ghost block. And also Items can be pushed through the worldborder.
Damian Luginbühl
You can push a block through the worldborder with a sticky piston. But the block moves through the worldborder. After that there is no ghost block. And also Items can be pushed through the worldborder.