Rafi screams "Gattaca" repeatedly through the paintball scene. He is confusing the cry "Attica" of Dog Day Afternoon with the Ethan Hawke film Gattaca.
Wilhelm Scream: When Taco throws the paint-knife during paint ball.
At the beginning of the paintball fight when Pete and Taco are in the bus, the lid on Pete's paint hopper is standing wide open which would have spilled his ammo when he lifted his gun up and down.