Continuity mistake: When T.J. goes back to the school to investigate the green light, you will first hear him say "9:20." Then a few shots later he says "9:23 and a half." Then one shot later, you will hear him say "9:22 and a fourth."
Suggested correction: No, absolutely not. When T.J. is watching the school from the bushes, he takes out his voice recorder and says, "9:32 A.M." Two shots later, he says, "9:32 and a half A.M." Finally, two more shots later, he says, "9:32 and three quarters." There is no mistake whatsoever.