Also: I didn't touch on this in my write-up because there's no definite answer. However, it's just a little oddity i noticed. The exploding milk bottles always light by themselves. The most noticeable instance is in the end of the level, but also in the vault and outside the asylum we see lit bottles, but no means of lighting them. Here are a few theories:
1. The game programmers were lazy and the idea of Boyd striking a match every time was a waste of an effort. I think this is unlikely, as Psychonauts is a relatively smooth-running and thorough game. The makers wouldn't leave something that might involve psychic powers unexplained.
2. Boyd himself is, and always has been, a psychic. This would make sense, as just a touch of pyrokinesis would be enough to light the fuse. Boyd is a little scatter-brained, so it's not like he would know how to tap into his powers in his state.
3. Prolonged exposure to psitanium gave Boyd powers. Again, unlikely. It took the cougars and bears generations to develop powers. Boyd is forty or fifty, at the oldest. Also, none of the other patients gained powers from the psitanium. It is possible that the psitanium boosted whatever powers Boyd may have had, but to grant him all-new abilities is unheard of.
4. Oleander transferred his abilities during hypnosis. This follows logic that runs along the lines of Oleander=Milkman, Oleander=psychic, so Milkman=psychic. I have no idea if psychics can pass on powers to non-psychics, though.