Other mistake: In the scene following the robbery, the four young men, led by Tupac Shakur and Omar Epps, run into a brick court, walled on four sides. Shakur states he's going to keep the gun, despite suggestions that they ditch it. He has a revolver stuck in his jeans, by his left hip. When he is challenged about keeping the gun, he pulls another revolver from his pocket, scuffles with one of his friends and shoots him in the chest - all the while the grip of the other identical revolver is in view.
Other mistake: In the scene after they rob Quiles' store and run into the abandoned house, when Bishop pulls the gun out on Raheem, there is another gun tucked in the front of his pants. They only had the one gun Raheem got from Sweets, where did this second gun come from?