As stated previously, the play sometimes diverges from historical facts in order to explore more fundamental and universal human issues and to achieve a dramatic effect. Only on the surface does it appear to be a composer's biography. Shaffer himself emphasises his intention: "From the start we agreed upon one thing: we were not making an objective life of Wolfgang Mozart. This cannot be stressed too strongly." (Shaffer 1993, 110) Still, this does not mean that Shaffer ignored and distorted historical facts. He based his play on thorough biographical research and only filled the inevitable gaps with his interpretation of the events (cf. Stumpf, 105f). It was his decision, though, which material to include and emphasise, which to leave out, and how to fill the remaining gaps. Following the logic of his premise, he has indeed created his own version of history.
The greatest liberty Shaffer took with the historical material was to build his play around the rumour saying that Salieri poisoned Mozart. This rumour arose shortly after Mozart's death and has haunted many minds ever since. The first to mention it in literature was the Russian poet Alexander Pushkin. In 1830, almost forty years after Mozart's death, he developed the subject into a two-scene verse drama revolving around envy, rivalry, and the role of the artist in society. This play was later turned into a one-act opera by Nikolai Rimsky-Korsakov. Although Shaffer claims not to have read the drama or seen the opera, his play seems to be a further development of the same theme and, at the same time, possesses a certain operatic quality.
In Mozart's letters, there are a few hints at a rivalry existing between the two composers, but not nearly enough to believe that Salieri played such an important role in Mozart's life as shown in Amadeus. The film takes even greater liberty with the historical events than the play. For example, Shaffer freely invented the scene of Mozart's death, where he dictates the last notes of the Requiem to the eager Salieri, as well as the scenes with the servant girl Lorl. Similarly, historical facts are sometimes distorted. Salieri's music, for instance, is shown as dull, simple-minded and "unworthy of his true abilities" (Brown). The motive of the masked figure is also changed. In reality, the mysterious stranger was not Salieri but a Count Walsegg, an amateur musician who wanted Mozart to write a requiem for his recently deceased wife and planned to present it as his own work.
The portrait of Mozart in Amadeus is rather accurate, but overdrawn and exaggerated. His letters, above all those to his cousin "Bäsle" (Anna Maria Thekla Mozart), betray his inclination towards scatological word-games. As Martin Esslin puts it, "[ ] in his letters Mozart reveals himself as an individual of earthy sexuality and scantological [sic] expressiveness". Nonetheless, it is hardly probable that he should use the same language in his relations at court. His "unforgettable [ ] piercing and infantile" giggle (Play, 24) is likewise an invention.
Finally, if Salieri really did commit a crime against Mozart, which, by the way, is unproven, it was not to destroy his rival by poisoning him but, more subtly, by preventing him from obtaining a secure place at court. It seems that this point will always remain open to speculation.