Irwin Allen managed to assemble his all-star cast by promising them they would only be filming for one day and that they would get paid $25,000 for doing so.
The film uses a great deal of stock footage from earlier movies, including Land of the Pharaohs (1955) and Helen of Troy (1956).
Since this is Harpo Marx's only color feature, it's the one movie in which audience members get to see that his wig was red, not blonde.