While it's not my favorite Disney film, I watched it so many times that I lost track over the years. I really can't wait for a trailer to see Tom Hanks and Victoria Summer's performances.
There are so many great stories about the making of that movie, going from the behind-the-scenes features on the DVD:
Glynnis Johns turned up for an interview with Walt Disney because when he asked to speak with her about Mary Poppins, she assumed he wanted her to play the title character. When she was clearly disappointed to learn he wanted her to play the mother, he tried to play up how good that part was by telling her that the Sherman Brothers had written a great song for her character. When she left his office, Walt Disney called the Sherman Brothers and told them he needed them to write a song for Mrs. Banks.
When they filmed the tea party on the ceiling scene, where they had to keep telling jokes and laughing Julie Andrews, Dick van Dyke, and Ed Wynn managed to crack each other up so much between takes that they couldn't stop laughing. The kids didn't get the jokes and couldn't figure out why they were all laughing. Matthew Garber, who played Michael, was afraid to get into the harness for when they had to float on the ceiling, so the crew paid him a dime after every take to keep him from trying to get out of it.
There was also a day when Garber, who was only seven, refused to smile. It was the end of the day, and the kid just had no smiles left. Dick van Dyke tried to help by doing pratfalls and funny faces, but whatever he did, the kid just glared at him and refused to smile. They never did get that smile that day.
Walt Disney's favorite song in the film was "Feed the Birds". He used to have the Sherman Brothers come to his office every Friday to play it on the piano in his office.
P.L. Travers, who wrote the original Mary Poppins books and was very critical of how it would be made into a movie, was reportedly still telling Walt Disney things she wanted changed at the film's premiere.
I also remember that Karen Dotrice, who played Jane Banks, actually burst into tears when talking about saying goodbye to Walt Disney after they finished the film. She loved him (Matthew Garber died in 1977, so sadly, he's not on the DVD features), talked about him like he was a favorite uncle.
They could make a really amazing movie out of this.