Brilliant music. That goes without saying; I mean, isn't that pretty much the point? But the way the music is woven into the plot - or is it the story is woven into the music? - so that everything works together so brilliantly is magical.
It's funny. I never noticed before that Salieri's got a total sweet tooth. I mean, I knew he ate sweets a couple of times throughout the movie, but I never noticed how food completely derails him. Second only to music, sweets are near and dear to his heart. Never is he more animated than when he describes Nipples of Venus to Mozart's young wife. It seems like whenever he reaches a key moment in his life and career, his fingers are reaching for a piece of candy. There's something rather cute about that.
But oh, the costumes. They're just stunning. Why don't we dress up in pretty ballgowns anymore?