Marijuana doesn’t cause hallucinations.
LSD, mushrooms, mescaline, peyote, and a couple of other chemicals can. Oh, alcohol can also cause hallucinations, but usually in mentally ill people.
The combination of alcohol and marijuana can produce some rather strange effects.
I don’t think that the authorities that reported that Wilson had so much marijuana in his system that he could have been hallucinating, was referring to the clinical interpretation of the word, but rather to the inability to interpret his situation rationally and act accordingly.