Display score while playing:
     Push Select while pausing.

Extra Ball + 1 Million Points:
     Get  to  the  bonus  round with green aliens and the skulls. Kill
everything  except  for  one  skull.  Keep  going  until a pteradactyl
displays.  Shot  the  pteradactyl  with  the  ball.  If  the  stage is
completed, you will receive one million points and an extra ball.