old Peter Behn auditioned with several other children for  the voice roles of Mother Rabbits children. When Behn said the line  (in reference to Bambi), "Did the young prince fall down?", a  casting director who was watching the audition in another room  shouted, "Get that kid out of here! He cant act!" However, the  Disney animators who heard the audition tape loved the sound of  Behns voice. Behn was called back to the studio, and the character  of Thumper was created largely based on his vocal performance.