Since it's showing a mix of short/long ones, the short ones at least should be the ones used by cavalry earlier (one shot and thrown away)
That’s a good catch. They had marksmen that retreated back as well, which explains the longer variants. Though this begs a different question, the ground is muddy and wet so the weapons on the ground (and the fuse) should be wet, and the pistols at least would have no ammo inside.
So Ike must have had his troops retrieve the weapons, prep, and reload them. Which, makes sense considering his approach of overly preparing for this engagement.
This kind of explains
Wait, they knew about the sword but nobody told him?
Because Ike knew he was going to fight the general anyway, regardless of how much he knew about the sword or what the sword was capable of, his options were then always: (a) beat the general in direct combat or (b) failing that, pretended that he lost, retrieved the weapons while the general thought Ike has lost, and peppered the general with bullets.