Absolutely you can trip on marijuana... Especially inexperienced users can have all kinds of mild hallucinations, mind-trips, panic attacks(!!) etc... And not everybody is living in California or Colorado, so they'll have to buy it illegally, and you never know what kind of shit the growers/dealers put in there to raise profits... Just look up "brix" or "haze spray". The latter is said to contain synthetic cannabinoids which can have severe hallucinogenic effects. But who knows... I have only smoked weed (regularly) and occasionally mixed weed with amphetamines (years ago) and I believe to have HPPD. Apparently, mostly eating junk food for most of my life hasn't helped, either... Also had little sleep recently because I quit pot, and a lot of stress/anxiety because of two illnesses I had recently at the same time (gastritis/peritonitis, which actually caused a panic attack because I thought I might die, which was increased by the pot, which is why I quit pot a couple days later). Now that I think of it, I definitely noticed the HPPD symptoms months earlier, while I was high, so I just thought it was me being high... The recent stress/anxiety/lack of sleep probably just made it worse/premanently noticable.