I found a bug where in the map bm_c4a3b2 where the “super” Alien Grunts show up. If your at the river (where they show up for the first time) and kill them their bodies will be on the air and act like they’re floating on water but in reality their just floating on the air and creating water splash effects.
When playing on the map bm_c4a3a ive noticed alot of ground is not solid which results in the player falling and dying, More specifically on those islands you have to jump on to make it to the combine building thingy. Please test it out and try making most of those surfaces solid.