It's obviously quite tricky to decide such things with complete accuracy, but -- reading Popehat's account -- it's not so much Eng's actual statements, but just the disconnectedness of thought that really leaps out. (See also the YT video someone posted.)
Robert Sapolsky also has an incredibly interesting couple of lectures on YT on schizophrenia. As it turns out it's actually recognizable in vastly different cultures, though not necessarily by concrete behaviors or mannerisms, but by persistent extremely erratic and destructive behavior. I can't recall the exact example at the moment, but I think it was something like "you killed the goat outside of the 'slaughering' season and covered yourself in its blood".