Didn't think I wouldn't like it...
You see, while your art style is acceptable, and the pacing makes the movie feel more epic than it already is, I have read quite a bit about the Columbine massacre, and there were 4 mistakes that I noted that were jarring enough to garner attention for me.
#1: While the pipebombs did have "VoDKa Vengeance" written on them, it was only partially because it was Klebold's favorite drink. The capitalized "DK" stands for Klebold's initials, and it doesn't make sense to keep them there when the character's name is Alex.
#2: In no account of the events have I heard Klebold tell Bruce Brown to fuck off; in fact, he specifically told Brown to go home, no cursing involved.
#3: No shots were fired before the killers entered the school. If they had done that, they would have alerted the students to the threat too early, and the fatality rate would probably be significantly lower.
#4: The teacher that was killed was busy herding the students to safe locations. He was wounded by one of the killers (I forget which one), and some of his students tried to save him (after they were sure that they were safe, too). He lasted for a few hours, then died.
Horrible tragedy; needed a fact-checker, though.