Many of the nannies stood in the large queue of applicants outside the Banks’ house at the start of the film were actually male actors in drag. In the book, Mrs Banks is the one to interview Mary Poppins for the nanny position rather than Mr Banks. Neither was she sentimental. Poppins had little time for the Bird Woman, the vagrant stationed on the steps of St Paul’s Cathedral, and on the issue of avian welfare in the capital went further even than Dawes Sr – “Feed the birds and what have you got? Fat birds!” – by suggesting they should be baked in a pie. Actor Stanley Holloway was considered for the role of Admiral Boom but instead he went on to star in the film My Fair Lady instead. I’ve been with Disney since 1989. I started not too long after college, so I’ve been here for 33 years, and 29 of that in the Walt Disney Archives. So, it’s obviously very important to me, a very big part of my life. I’m very emotionally attached to Disney; I love the company, and I love what I do. I often get questioned by people who say, ‘Oh, you have my dream job.’ And I have to admit that, well, yes, I do. I have my dream job. It’s such an honor and a real blessing in my life to be able to work with the people that I work with. I think probably my favorite part is working with all these extremely talented people and supporting the work that they do.

The scene where Mr. Dawes, Sr. has trouble with the step in the bank room was not originally in the script. While viewing a make-up test for Van Dyke in the projection room, Walt Disney saw him entertaining the crew between takes with some comic routines. Including the “stepping-down routine” of an old man trying to step off the curb. Walt Disney specifically requested that the Mary Poppins crew members build a six-inch riser on the bank room set so that Van Dyke could do the stepping-down routine. Pre-production of Mary Poppins and song composition took around two years to complete. The Sherman Brothers (Robert B. Sherman and Richard M. Sherman) came up with the idea of Mrs. Winnifred Banks (Glynis Johns) being involved in the suffragette cause to explain why she should be so neglectful of her children. Mary Poppins quotes John Keats' "Endymion" when she says, "A thing of beauty is a joy forever", as she pulls a plant pot out of her carpet bag. This is the same Keats line used by Gene Wilder in Willy Wonka & the Chocolate Factory made in 1971.One of Julie Andrews' favorite songs in Mary Poppins was "Stay Awake." When she heard that there were plans to cut it, she wrote a letter of concern to P.L. Travers who instantly insisted that the song remain in the film. To re-create that base, Cline hired well-known designer Kevin Kidney in 2007. No stranger to designing for Disney, Kidney has worked on everything from theme park show props to collectible merchandise. “The original snow globe was handmade by one of my art heroes—Disney Legend Rolly Crump,” says Kidney.“The glass portion with the cathedral was on display in the Archives, but the metal base had been missing for nearly 50 years. I was able to re-create it from production stills and screen shots.” The word "supercalifragilisticexpialidocious" was not created for Mary Poppins. A variation was first used in a 1949 song by Gloria Parker and Barney Young. They did sue Disney for plagiarism, but lost after the lawyers showed that a similar word had been used by Helen Herman in the "Syracuse Daily Orange", a college newspaper, on March 10, 1931. Herman wrote: "Several years ago, I concocted an expression which, to me, includes all words in the category of something wonderful...I believe that I am the sole originator of it, or at least, I have my own interpretation of its pronunciation… it implies all that is grand, great, glorious, splendid, superb, wonderful." When the Founder and Chief Archivist at the Walt Disney Archives, Dave Smith, went on a search for the Snow Globe from this Mary Poppins, which includes birds flying around St Paul's Cathedral, he found it on a shelf in a janitor's office. The janitor explained that he saw the Snow Globe sitting ready to be thrown away, but liked it so much he kept it for himself.

Disney is one of the most recognizable companies and brands in the world, with a long, rich history. How do you help not only preserve that history but share it with the world? Mary Poppins herself was originally written as strict and pompous in the books but Disney made her kind and gentle as well as keen on discipline. The character of Bert is actually a mix of several of Mary Poppins' friends from the original books. Among them is the minor character of a chimney sweep. It was a drawing of the sweep by one of the animators that inspired the film’s song "Chim Chim Cheree".The author of the Mary Poppins books, P.L. Travers approved of the casting of Julie Andrews after hearing speak over the telephone. Andrews granted the interview from her bed after the delivery of her daughter, Emma Walton Hamilton.