According to this former soldier, the message that director Hayao Miyazaki hid in morse code has never been revealed until now.
According to Sakai, the second morse code scene also has another hidden message.
According to Sakai, who is now a TV director, there are three scenes in the film where the morse code can be heard, with the first being early on in the movie.
Take a look at the first morse code message in the clip below.