I've hallucinated twice from weed. Auditory hallucinations. I heard fucking voices, man, creepiest shit in the world. First time I was retardedly high, walking around a neighborhood lake at like 2am by myself. I was going to meet with somebody, can't remember who... but as I was walking, slowly but surely I started to hear massive amounts of chatter. It was like being in my high school cafeteria and being surrounded by 400 people all having separate conversations, the noise blurring into a massive, unintelligible background noise.... but I was the only one on the lake. That shit was weird but I was excited about talking about it, for whatever reason.. Can't remember how much I smoked but it was back in the days of rolling up an 8th of midgrade for a session, so it was probably around 3.5g.
The second time happened in the past year. I was just chillin', smokin' the usual amount while I watched some TV. I was kind of zoning out thinking while I stared at the screen and listened to a conversation, and the next thing I knew my internal voice was sounded nothing like my own, and was "saying" things that didn't fit my personality whatsoever. They weren't unsettling, it just felt like it wasn't me, you know? It was like a part of my head went on autopilot, man, I couldn't change my internal voice/dialogue back to normal. It freaked me out so I took a Benadryl and went to sleep, lol.
I've never had a visual hallucination from weed, though. I can't even imagine what that might be like...