Professor just gave an exam that was way outside of the scope of the class, various other issues with assignments, what should the class do? 80% of the exam was super in-depth questions about a topic glossed over for fifteen minutes about six weeks ago, with no prior warning. Its a relatively large class and most students are very perturbed. 

There have been other issues with this professor including mistake-filled assignments, assignments given out late, reducing the amount of time students had to work on them. The instructor is very disorganized and does everything at the last minute, and consequently so are the TAs.

Who should the students go to first?
Actually, I don't think there is much you can do. Professors and administration hear complaints about "unfair" or "too difficult" exams all the time and most of them are exaggerated. 

If your university has some official representation of students, you should go to them so that they can bring up the issue at an appropriate place. And you can hope that the professor sees that the results of his exam are very poor and that he reacts to it.