 SPOILER: Paul Thomas Anderson (qv) has said that he was unaware  that the story of frogs falling from the sky is in the Bible (he  took it from Charles Forts writing) when he wrote the screenplay.  The Bible story of the plague of frogs was brought to his attention  by Henry Gibson (I) (qv) prior to filming. After he became aware  of the story, Anderson worked references to Exodus 8:2 into the  movie.