Ah yes, the infamous "weapon malfunctions".. ie: I'm in the process of firing some weapon and I get insta-killed by somebody at the same time and it says I killed myself.
One possible explanation is that explosives are detonated when shot (notice you can detonate TD's for example in mid air with other TD's or even bullets). It could be the person is hitting your explosives the instant they come out of the barrel and the animation is just too slow to show it.
On the other hand, yes, I've seen it happen with non explosive weapons too so something must be up.
I am guessing there is something up with the headshots/scratch2,3,etc counts. Perhaps the log files are goofed up so it counts too many of them early on then not enough later. I never get headshots anymore, but I figure I must be earning them because I hit somebody in the head and they go down.
Wonder if deleting the log files or reinstalling would fix it?
As to the falling thing, yeah, sometimes it seems like you take a lot more damage from short falls but not from long falls (Ie: leaping out of the base window to the raised floor on ghost ship you usually don't take any, but fall from the heavy repeater platform and you take a lot of damage).
If you're spectating a person and they disconnect, your view follows their corpse as it falls through the map and falls in darkness forever. Whoa.