This was the first film that used the technique later known as Dynamation. This involved using a split screen technique to insert models into the live-action. It was a method of seamlessly integrating the live-action with the models. The film was Harryhausen's first solo feature film effort, and a major international box-office hit for Warner Brothers Pictures.
It is worth noting that Ray was able to develop and execute most of the miniature set work himself, thereby saving money and more importantly maintaining his full technical and creative control in order to achieve the desired special effects in his films.