The narrator should have vocally appeared in this film as well. He was real good (though they obviously played with his voice in the editing room).

This film was made during MGM's scifi-era. Gone were the days of 'Wizard of Oz' musicals. This era they produced this, 'Soylent Green', 'Westworld'.

At youtube put in "Night of the Lepus (trailer)" and "warnerarchive" and you can see this trailer. (The link is hard to write. There is a letter that is just a straight line and I do not know what that is!) Look Warnerarchive like in Warner Brothers.