Even sadder - it is based on a play by Peter Schaffer (of Equus fame). His mania, his sexual appetite, his gauche manners, his inability to focus unless pushed are all accurate. Salieri despised him, more because he (S) was a man of modest musical talent confronted with a swaggering, braggartly, giant of musical talent. The bit about too many notes is accurate.
The Requiem was finished after Mozarts death by one of his students at the request of Constance. 'His grave has been found, but of course as it was a mass grave dealing with the health issues of the plague sweeping the city at that time, his individual bones have not been identified.
There has been some speculation that Mozart suffered from both Tourrette's syndrome and ADHD, but nothing denies his ability to write music without reference to keyboard or other instrument.
Contemporaries of Mozart do indicate that he laughed like a donkey braying, so there may be some verisimilitude in the acting.
