Actually, Hal Warren took it very seriously, even though all the cast was already calling the movie "Mangoes: Cans of Fruit" during the filming, from what I read.
That's what makes it so sad -- he thought it was good. He even had a limo take the cast to the premiere, and they were all horrified when the crowd started laughing and booing. I know it sounds contradictory, but I think he had convinced them that it was good.
Man...talk about delusional! That IS sad.