One of the funniest bugs I remember trying to help with was trying to find out why projectiles were magically getting destroyed in one of our zones.
Everyone got together, very serious; QA and developers to try to figure out what it was. You know what it ended up being? Chickens. Someone by mistake made the sound colliders on the chickens massive and put them on the wrong layer. Every time you shoot an arrow or a fireball those projectiles would bump into the collider and disappear.
Whenever I think about that day I laugh to myself, I just picture these demi-god chickens walking around with supersonic clucks, hahaha.