 PLOT: Russell makes a tape recording of what he fears will be his  last message. He mentions that the flying saucer sound can be found  on the same tape, and says he is stopping recording because the  machines battery is running low. For no reason he then switches the  recorder to playback, without rewinding. Its offspeed playback then  reveals the message in the sound. This means he must have been  placing his message on a part of the tape where, if the battery had  not run low, it would have obliterated the sound.