Living in the area, I was well aware when this tragedy occurred.
My nephew was also an assistant coach on the team (but not portrayed) so I know from him how accurate the portrayal is, as well as knowing Kathy for decades.
Bres is very matter-of-fact, and suffers no fools, but she's not quite as calloused as portrayed on screen. That being said, it's understandable to create drama to perpetuate the story with a sort of antagonist.
The timeline is a little 'off', and the difference between semifinals & finals is only a day- but again, plot development, so it's necessary.
Other than these very small details, I found the film to be very good, Helen Hunt absolutely nailed Bres' wardrobe to a T!
I recall the ICW football team also honoring 'Line' during their season, and the entire state really did rally around these kids who suffered so mightily.
It's a wonderful portrayal of events, and how drive and determination really can propel you to the top, and honor those left behind.