The second way to analyze this film is as a factual account of history, and here is fails resoundingly. It is true that Peter Shaffer himself calls it "a fantasia based on fact. It is not a screen biography of Mozart, and was never intended to be." The argument, of course, is to say that this film gave many people that first real exposure to Mozart, and as a result, gave them untruths upon which to base their knowledge. That is to say, to the everyday person who knows nothing of Mozart, there is no reason to think the events described in Amadeus are anything but the truth. Why perpetuate rumors and myths, when the truth is available?
I choose not to enter into this argument. There are valid points to be made on either side. I will, however, point out some of the more glaring "mistakes":

~~ While the movie shows the dying Mozart dictating his Requiem to Salieri, it actually was his pupil and assistant Susmayr who helped him with it and finally completed the score. The existence of Susmayr, as well as that of Lorenzo da Pointe, is nowhere mentioned in the movie, though they each played a far more critical role in Mozart's life than many of the characters who are shown in the film.

~~ Constanze Mozart may have been prone to spending time at the spa in Baden, but she never packed up and ran out on her husband, as she is made to do in the movie. Nor did she ever throw Mozart's father out of the house. (Though leopold's visit WAS very disastroud and he ended up leaving of his own accord.)

~~The Mozarts had two surviving children, not one as depicted in the film. Additionally, four children died in infancy. There is a reason for this, though: Milos Forman didn't want children taking center screen, he wanted the plot and more prominent characters to be played up instead.

~~Salieri never planted a servant girl in the Mozart household as a spy, and it wasn't him who commissioned Mozart to compose the Requiem. ~~Neither Mozart nor Salieri ever conducted an entire performance with two hands; the late 18th century practice generally was to conduct from the keyboard. This is one of a number of stylistic gaffes in the movie. Though it's true that in one seen in the movie, Mozart is shown at an outdoor concert conducting from the piano.

However, a third element overpowers all of these concerns as to the worth of Amadeus. The presentation of Mozart's music is breathtaking. Whatever other criticisms there are to make of this film, it cannot be denied that it brought about a re-emergence of Mozart's works into popular culture. One of my favourites is the Serenade for Winds, K. 361, 3rd movement. As Salieri describes, this piece is exemplary of Mozart's true genius: simplicity crafted into the complex. The interweaving melodies become impossible to separate, and yet never cross the line to cacophony. I remember, when I first saw this movie, hearing Salieri describe the beauty of this piece -- the clarity of the oboe, and the lovely tune of the clarinet -- and becoming just as entranced myself by its long, mesmerizing journey to a final cadence.
Also impressive is the inclusion of the Requiem, K. 626, in its entirety. The death-bed composition scene in Amadeus may be a bit unbelievable, but the use of various movements to accompany Mozart's dying, Constanze's return, and Salieri's passion is clever. The movie begins with the furious Symphony No. 25 in G minor, K. 183, and ends with the deceptively simple Piano Concerto in D minor, K. 466, 2nd movement. So begins and ends Mozart's life, in Peter Shaffer's Amadeus, and perhaps everyone starts and ends that way: starting off in a fury of noise and vigor, and in the end, slipping away quietly with time-taking ease.