Comment by Mable Esterfield on Star-Embracing Swordmaster - Chapter 18

I don't get the fact of them having to step off their horses when the worm passed, perhaps the novel had an explanation, which they deemed too long to put into tje manhwa, but now it's just confusing for the readers. 

Besides that, why were there extra men, without any weapons on them at all? They didn't even wielded spears or anything.