http://en.wikipedia.org/wiki/Koyaanisqatsi
"The film consists primarily of slow motion and time-lapse footage of cities and many natural landscapes across the United States. The visual tone poem contains neither dialogue nor a vocalized narration: its tone is set by the juxtaposition of images and music. Reggio explains the lack of dialogue by stating "it's not for lack of love of the language that these films have no words. It's because, from my point of view, our language is in a state of vast humiliation. It no longer describes the world in which we live."[2] In the Hopi language, the word Koyaanisqatsi means "crazy life, life in turmoil, life out of balance, life disintegrating, a state of life that calls for another way of living"."
It might be difficult to find this film in HD though. It has some mind blowing visuals and a philosophical message - if that's the way you want to go.![]()

I second the Animatrix.
That shit is hard.
I checked out the Animatrix second renaissance last night, I found it quite disturbing. I would not watch that whilst tripping!
The movies people have mentioned such as Waking Life, Enter The Void, Animatrix, Eternal Sunshine of the Spotless Mind, Naked Lunch, Donnie Darko etc, all the classic headfuck films are all far too dark and creepy for watching under the influence of a psychedelic like LSD or shrooms. I just don't know how you can even think of watching those whilst tripping, the thought makes me almost physically sick.
A lot of interesting movies have been suggested, in my opinion however some of them are very inappropriate suggestions for this thread.
For example Gummo or Waking Life are nothing like what the OP describes he wishes for in a movie, don't get me wrong both are very good movies but watching Waking Life stoned was enough to take me on a wild ride and I wouldn't say I'm that sensitive to this sort of stuff.
Another suggestion I don't agree with is Enter the Void which in my opinion is just a pretty movie that lacks substance and doesn't have much to offer.
Winged Migration, the recommended nature documentaries, Ashes and Snow, 2001: A Space Odyssey and if you feel like pushing yourself a bit but probably in a worthy direction Baraka and Koyaanisqatsi. Oh i'm not sure if it was mentioned but the BBC doc Life narrated by David Attenborough is another great choice, at least it worked for me while on a Morning Glory trip.
The plot of Inception is impossible to follow totally even straight on my second viewing. You need like a notebook or chart to diagram out what level of whose dream they are in etc. Yes some wild visuals, and an awe inspiring atmosphere, but throw in drugs and you will basically just be on a visual roller coaster. I saw it first time on a modest amount of 2C-I and it was a fun and intense "out there" experience, but I had NO idea whatsoever what I had just watched, just a confused jumble of a movie, a film-school project of "Lets see how complex you can make something on film and what that severe level of uncertainty about what is going on has on the viewer." And the acting is totally flat and dull, you really cannot give the slightest fuck about what happens to these robotic characters who really dont seem to care about anything themselves.
On the other hand Waking Life is ABOUT the nature of consciousness and reality and the mind, and visuals are the perfect mix of simplicity and suggestiveness for your tripping brain to fill in lots of fun stuff with the acid visual effects. A simple enough plot to be able follow drugged, but with lots of food for thought. You ought to add that to your list.
After a few hours we watched Inception, with a crazy 3D-layer on top, it was very nice. On this low dose we could follow the story line quite well.