I have hallucinated on pills many a time, in fact many more than I have when taking trips. Very very deatiled visions as well, I was once watching a spider crawl around my ceiling for approx 45 minutes, describing it in detail to my g/f, it wandered around, I could even see the hairs on its legs bristling in the wind. Ive seen Victoria Park swimming pool packed with atleast 100 people swimming laps at 4:00 in the morning, one hallucination almost like animated cartoons, but with stick figures instead of people, one was riding a mammoth, one was on a turtle diving into water, there was a frog, all where flowing like a movie on my ceiling (the cause, several paint 'marks' on the ceiling that joined together after a while looking at it), Ive had little men run at me, like those jawa's in Star Wars, with bright yellow eyes and holding unbrellas, they ran through the car at me, quite freaky, though always in the back of my head remember that it isnt actually happening, even though you can still fool your mind sometimes.
I have thought about hallucinations at times, trying to describe it. For me hallucinating is like reverse vison. In normal vision our eyes see things, the picture is transfered to the brain where it analyses the image and tells us what it is. To me hallucinating is my mind thinking of something, or a particular image, and then my mind making my eyes see the picture, as if it was really there. I can think about something and make it appear in front of me if I am in the hallcintaing mood.
Another big cause of hallucinations for myself is sleep deprivation, it makes me hallucinate more than any drugs, though usually my lack of sleep is brought on with the help of drugs. I was hallucinating non stop, even in the daylight (noramlly I hallucinate only in the dark or house lights, but not daylight) after a 5 day goey bender, all with no sleep.
I suppose hallucinations can be dangerous in different circumstances, I know id hate to be alone somewhere i didnt know, in the middle of the night seeing visons, but then again id never put myself or get into a situation like that on drugs.
Have responsible fun and enjoy the free movies in your head