One improvement I would like to see made to the college replay system is to do it more like the way they do it in the NBA. After a review/challenge in the NBA the ref actually explains why a call is changed or not. It usually goes something like the challenge is successful/not successful because of XYZ. The lack of a real explanation to why a call stands or is overturned means there is no transparency to the process.

As a little bonus I also think targeting should also take a cue from the NBA and it should have levels like flagrant fouls where they are both a 15 yard penalty but only the highest level gets a player ejected. All targeting is reviewed anyway so that is a judgement that can be made during the mandatory review.