Thanks! The disc doesn't follow the exact path! It actually uses an accurate simulation of the discs flight paths. I've added bunch of the most popular Innova discs to the game along with their manufacturers stats ratings. You can learn a bit more about it here: https://www.innovadiscs.com/home/disc-golf-faq/flight-ratings-system/
Generally, when throwing a right handed backhand (the default) the disc will fade off to the right at the end of the flight, and vice versa with a forehand.
I'm planning on making many more additions to the game, and there's already a lot of changes from 8 days ago. One of those things is a tutorial explaining WTF is going on with the disc not going straight.