for awhile i'd have anxiety attacks when i smoked weed. i stopped smoking weed, but continued to have anxiety attacks - ones involving depersonalization - but when i got my anxiety under control (by making changes to my life) i stopped experiencing depersonalization. and now i can smoke weed again without problems. so, basically, depersonalization is probably related to anxiety more than it is related to weed. but, ya know, the whole point of smoking weed is to alter reality. maybe you are just getting too stoned.
theres a chance that weed was laced with something, although i doubt it. sometimes that just happens... marijuana is a strange thing, but still amazing.
I have a tendency to look in the mirror when I'm stoned and be like, that's ME?! It seems foreign to have a face when I'm high, not sure why. Maybe my eyes just look weird. But I'd say this isn't too much of a problem. Weed isn't everyone's thing. Just don't do it anymore.
I had your problem real bad OP at one point. Felt like a serious matter at one point, but I really think it just comes with the high sometimes. You can feel it out and respect it as it's own thing. Try not to let it alarm you, don't be surprised. Anxious quarrels tend to always pass too especially if you can focus and slow down your breathing.