The top mistakes in The Manhattan Project http://www.moviemistakes.com/film2684 en Sat, 11 Oct 2008 05:55:29 +0000 116965 In an early scene, the high school science teacher produces a schematic diagram of the two nuclear bomb designs created by the Manhattan Project. He says, "Here are two designs based on plutonium." Actually, only the Fat Man bomb uses plutonium. The other, the Little Boy design, uses uranium.