Trivia: The green dress Maria wears when she returns to the von Trapps is the exact same dress as the new postulant is wearing as she enters the Abbey. My guess is that the new postulant was Julie Andrews' understudy and was used in the scene instead of casting another actor or extra. (02:01:02)
Suggested correction: As she said earlier in the film, when women join the convent, they donate all their worldly clothes to the poor. Maria likely did that when she returned from the von Trapp household. As the new girl was joining, she had to give up her worldly clothes. Since Maria was sent back to the von Trapps right after this, she likely grabbed this dress so she could get back there. As this is a film and not a play, Julie Andrews would not have an understudy, as they would have to reshoot the entire film anytime her face is visible.
