When Travers arrives in her hotel room, there are two Winnie the Pooh dolls among the gifts, showing Pooh in his redesigned appearance from the late 1960s. Walt Disney's merchandise licensee did not yet have the toy rights to this character in 1961.
Several changes had been made to real-life Disneyland to make it look like how it was during Walt Disney's lifetime (i.e., the area in front of the train station is lined with posters advertising the park's attractions). However, Fantasyland remains unchanged despite going through a complete overhaul in 1983, some twenty years after the release of Mary Poppins.
When Mrs Travers arrives in her hotel room she pushes a button on the remote and the TV comes on immediately. In 1961 when the movie is set, TVs used vacuum tubes and it took a couple minutes for the TV to warm up. The first TV with an "instant on" feature wasn't marketed until 1968 by Westinghouse.
While Walt is escorting Mrs. Travers down Main Street USA, the sign for "Great Moments With Mr. Lincoln" can be seen in the background. That attraction did not open until 1965, after Mary Poppins had been released.
The blue Australian National Flag (Blue Ensign) is shown at the Allora fair in 1906. The mainly white Australian Federation Flag was, alongside the Union Flag, the most popular flag at public events from 1901 until the 1920s. In 1906 the Blue Ensign could only be flown from military buildings, and on other government buildings if no other flag was available. From the 1920s to 1950s, the most popular Australian flag was the Red Ensign. The Blue Ensign was not formally adopted as the Australian National Flag until 1954.
On her ride from the airport to the hotel, Mrs. Travers' limo passes several light posts of curved metal tubing and arc lamps which did not exist in 1961. Also, at the entrance to the hotel we see the base of a tapered metal telephone pole with metallic clamps, that style did not come into use until the 1990s.
As Walt greets Mrs Travers from the limo at Disneyland, a man standing behind them snaps a picture with what is clearly a Kodak Instamatic camera. This takes place in 1961 and the Instamatic was not introduced until 1963.
The film shows the license plate of the limo as three digits followed by three letters. In California, license plates at the time were three letters followed by three digits; three digits followed by three letters were not used until 1969.
In the finest tradition of movie billboards and DVD covers everywhere, the new poster for Mary Poppins credits "Julie Andrews" above the face of Dick Van Dyke, and "Dick Van Dyke" above the face of Julie Andrews.
Scenes of the audience reacting to the film at various points are lit with changes intended to give the impression that they are watching the film, however the aggressive changes in ambient room light are inconsistent with the scenes being implied on screen.
The railway destination board, at Maryborough Station contains a number of errors. There is no such town as Vandina, it is actually Yandina. Grandchester is incorrectly spelt as Grgandchester. The stations shown below Brisbane are not on the old Gold Coast branch, but are inland, with the destination, Allora, a real town, approx. 150km inland from the Gold Coast.
When Walt Disney greets P.L. Travers at the main gate of Disneyland he greeted her with "Welcome to the Magic Kingdom". The Disney Park in Orlando is called "The Magic Kingdom" not Disneyland in California.
Travers Goff is depicted clean shaven in all his scenes in the film, and Pamela insists that Mr. Banks must not have a moustache in Mary Poppins, for this reason. However, Travers Goff's photographs show him with an even larger moustache than David Tomlinson's Mr. Banks had.
When Walt and Mrs Travers arrived in Disneyland for a visit in the morning with people were queuing for the gates to open the clock tower at the train ride shows it was filmed about 3:30pm. This appears twice on screen.
At the beginning of the film, the cherry trees in London are blossoming - Travers refers to them as pink clouds on sticks. When she returns two weeks later, they are still in bloom. Cherry trees are in bloom for only a few days so the shots were definitely not filmed two weeks apart.
Mrs.Travers finally grants Disney the film rights to her books, except she signs the wrong page of the contract - the Witness page, in the space reserved for the person in whose presence she should've signed the Signatory page. She cannot legally be her own witness; and what is more Mr.Disney's signature is also invalid since nobody witnessed that either, as shown by the unsigned space further down the document.
The machine supposedly playing an archive recording in the closing titles begins near the end of its tape, which dramatically runs out as the credits move on. However, since these recordings were in effect contractual documents, each negotiation session would have begun with threading a fresh tape; not one with such limited time.