During the shooting of Forman's Jim Kaufman biopic 'The Man in the Moon' Carey allowed himself to be filmed off camera (so to speak). This was particularly brave of him as it turns out his obsession with Kaufman turned him into a very outlandish person (and I'm phrasing it nicely : Universal only recently released the footage as they feared it would "make him look like an asshole").
'Bizarre' is a frequently stated assessment of the situation and seems 100% adequate.
Quite fun to watch, therefore! Carey provides present-day, insightful comment and there is also ample archive footage of Kaufman himself, embodying the adjective 'bizarre' just as much as Carey did.
My one regret was not seeing more of one of my favourite directors, Milos Forman.