Hmm, let's see, I'll start with a few simple ones, and add more later (when I capture some vids).
1) Compound back wall, does not function as a wall at all, can be shot through both ways if any survivors are placed in the top left or top right extremes of the compound's exterior.
2) Towers placed in certain positions seem to be able to either shoot through the roof into the compound; or through some gap above doorways that appears as a wall, but presents them with a LOS not available to ground level survivors in the same position, (this is different to #1).
3) Defenders do not shoot at my survivors even when I step into their 'Effective Range', as long as I do not shoot at them. E.g. I can walk to within about 20m of an enemy survivor that has an effective range of 40m, as long as my weapon range is less than the distance between us (to prevent my survivor auto-firing). I have tested this with friends, and it takes away some of the benefits of range, though maybe that was your plan, but still, it weakens certain types of compounds quite considerably, especially considering that high range weapons are already weakened by relatively low DPS. Though as I say, I suspect this one may be part of your plan, rather than a bug.
4) Sometimes when angling out an enemy survivor (isolating them from the group they reside in by using the compound as a block), certain enemy survivors that don't have LOS on my survivors will still start firing at my survivors even though I can't fire back at them because the compound is in the way. This one doesn't always happen, but it is common enough to be a problem.
5) Scavenging through walls when certain objects are close enough to the wall (not tried this one in a while though).
6) Grenade blast radius extends through walls to enemy survivors, not sure if this is a bug, or just a way to balance out that grenades don't destroy the compound walls they explode near, even though in RL they would.
7) Baiting an enemy survivor: If enemy survivors are assigned to a barricade but not completely 'sealed in' you can step into their LOS take a few shots and step back out again, which will cause them to run through the compound grounds towards you, and towards their inevitable death. Also, there are other times when I try this, that the enemy survivor runs around in circles like a headless chicken (rather than running towards me), and he will keep running in circles until shot dead.
8) Sometimes at the start of a raid my survivors do not spawn properly (no matter how carefully I select the spawn area), e.g. when selecting a spawn point behind the car and similar cover, 1 or 2 survivors sometimes spawn about 1 meter away from cover while the other survivor spawn in the correct area. This presents a problem with certain compounds as it means a quick death before a smoke can be placed down to reposition, though thankfully it does not happen all the time.
9) Excessive enemy distraction: If you shoot at the enemy survivors and switch between them quite quickly, you can distract (but NOT suppress) all 10 to the point where you can just walk a guy right up to them with melee and kill them all 1 by one. Occasionally it backfires and they do shoot the melee guy, but 7/10 times this works. I have even seen other raiders become so complacent that they use their melee guy to disarm traps along the way, all the while standing in the open with all 10 unsuppressed enemy survivors having LOS on him/her, yet remaining unharmed.
Still quite a few more, will update when I can.
Edited by BrianBore, 29 May 2013 - 04:29 AM.