Frequently Asked Questions
It's indeed mortally dangerous for a normal human being like VIncent even to attempt such a reckless act. However, Irene was genetically designed like most (if not all) of the drivers in the highway, so it could be argued that most of the Valid (genetically enhanced individuals) have far better senses and reflexes other than the InValid or God's Children (normal human beings), and an inherent lowel level of fear in front of dangerous situations. Note how Gattaca's world seems to have no traffic light whatsoever, for instance. Maybe they are not needed at all.
The piece played by the six-fingered pianist (http://www.youtube.com/watch?v=w5FowPApEzY) is a variation on Impromptu in G Flat Major, D899, No. 3. by Franz Schubert (1797-1828). The original version is obviously possible to play at 10 fingers (for instance, watch this version: http://www.youtube.com/watch?v=L6_SbflSwAg), however, Michael Nyman (who composed the entire soundtrack and made this arrangement) did a beautiful job embellishing the piece with additional notes/harmonies to something that "can only be played with twelve" fingers, as the Irene Cassini (Uma Thurman character) notes. The piece was digitally composed from the human-capable pieces put together with the impossible to play ones.
Many experienced pianists have noted how this variation is in fact impossible to play by human beings, not only because the lack of additional fingers, but also the uncomfortable way it would be to attempt it as a duet.