Revealing mistake: Whenever Ralph is driving Travers in the limousine and the exterior of the car is seen in a long shot, there is no one riding in it other than the driver. From every view point of the windows that can be seen, there is no passenger inside where Travers is supposed to be seated.
Saving Mr. Banks (2013)
1 revealing mistake - chronological order
Directed by: John Lee Hancock
Starring: Tom Hanks, Colin Farrell, Emma Thompson, Ruth Wilson
Factual error: When Mrs. Travers arrives at the airport, there's a driver holding a name-card with a Warner Bros. Television logo on it. It's a far more modern version of the logo, however - in fact, the word 'Television' didn't appear in the ribbon across the shield until 1994. (00:10:10)
P.L. Travers: I will not have her called Cynthia, absolutely not. It feels unlucky. It should be something warm, a bit sexy. How about Mavis?
Trivia: In the final scene from Walt Disney's office when P.L. Travers has arrived for the premiere you can spot a map of Florida with a marked area of where today's Walt Disney World is located. Walt Disney was indeed planning WDW in 1961 and it was in the early stages of development on the drawing board. Ultimately, Walt died before the new park opened. (01:50:40)
Answer: The dog is either a Skye terrier or a French Briard. Since it is white and has a long tail it is most likely a mixed breed, since the scene is supposed to be in Australia, it may be a mixed terrier and Australian sheep dog mix.