 The film makers didnt inform Karen Dotrice (qv) or  Matthew Garber (qv) about some "surprises" that were going to show  up in the movie. Karens dumbfounded look when Mary Poppins takes  out item after item from the carpet bag and her little scream when  Mary Poppins gave them medicines of different colors were genuine.  They also didnt tell the children who was acting as Mr. Dawes Sr.,  and were worried that the horrible old man was going to fall down  and die at any moment.