The film ironically helped spark a revival of Salieri's music, which had previously languished in obscurity.
When shooting the scene in which Salieri is writing down the death mass under Mozart's dictation, Tom Hulce was deliberately skipping lines to confuse F. Murray Abraham, in order to achieve the impression that Salieri wasn't able to fully understand the music being dictated.
Several professors of music stated, after studying all of the musical keys struck on pianos throughout the film, that not one key is struck incorrectly when compared to what is heard at the exact same moment. In other words, what you see is exactly what you hear.
Milos Forman insisted that his lead actors retain their American accents so that they could concentrate on their characters and performance instead.
The performance of "Don Giovanni" in the movie was filmed on the same stage where the opera first appeared.
Milos Forman: [Schiavelli] Vincent Schiavelli appeared in almost every Forman film. Here he's Salieri's valet.