 Ann Miller (I) (qv) danced with pinched nerves in her back. Also,  she was too tall, so she had to wear flats so she wouldnt be taller  than Fred Astaire (qv). The evidence of this can be seen towards  the end of the movie. When Ann Miller finishes the number "The  Girl I Love" she goes behind the curtain wearing red high heels;  when she comes back out in front of the audience to entice "Fred  Astaire" to dance with her to their old song "It Only Happens When I  Dance With You", she is wearing red flats.