While the movie is a good effort, well, decidedly that, the characterization of Mozart is rather off at times, such as here where Tom Hulce begins by doing his Sally Fields impression: "you like me, you really like me!" And ends by directly contradicting the emperor, something a tad unlikely.
Ironically, while the real Mozart, as opposed to Haydn, luxuriated in a wealth of themes in his music, you really couldn't accuse him of writing too many notes. That honor should be reserved for people like Jan Ladislav Dussek, who was famous for never writing one note where he could write a dozen. He was an influence on the later composer/pianist Franz Liszt who also excelled at excess.
Let's have some examples. First of all some piano music by Mozart. This is the Piano Sonata No 16 C major, K 545, played by Daniel Barenboim:
Now for some Dussek. This is the first movement of the Sonata op. 75 in E flat major, but we are not told who the performer is:
At first you might think it sounds a lot like the Mozart and they do share the same musical vocabulary. But as the music progresses I think you might notice the redundant octaves, the fortes and the repetition just for the sake of repetition. Dussek tends to just overdo everything. But for the real specialist in too many notes we have to turn to Liszt. Here is his Transcendental Etude No. 4:
Apologies to all the pianists out there, but the piano seems to specialize in wretched excess, probably because it is a very cleverly designed mechanism for producing the greatest number of notes with the least effort. Though there are quite a few examples for the guitar as well! Of course, the great composers did not fall into the trap of writing "too many notes" but just the right number. This is the Haydn Piano Sonata nº 59 in E flat, Hob. XVI:49 played by Alfred Brendel: