Shot back-to-back in Puerto Rico with The Last Woman on Earth, using the same cast and crew, but not released until several months afterward.
The scene of the Cuban military officers saluting as the little boat they are floating in sinks was not planned; it actually began sinking as they were completing the shot. Roger Corman told the actors to stand and salute as the boat sank and filmed every moment, later stating that it 'wasn't very deep' there. He also gave high praise for the Mexican actors that played the officers for taking direction so well.