During the Nowhere to Go but Up sequence, when everyone floats away on balloons, Gooding is clinging to Frye rather than floating on a balloon of his own. Why? Because he had much more enthusiastically assisted Wilkins in screwing over the Banks family than Frye did, so much like Wilkins, a balloon wouldn't work for him. Although unlike Wilkins, he seemed willing to see the error of his ways and give good-natured whimsy a chance, hence why Frye apparently let him share a balloon.
During A Conversation, Michael asks the biggest question on his mind, the one he says he most longs to know: "My question, Kate, is: Where'd you go?" Of course, Mary has the answer: The Place Where Lost Things Go.
Jane becomes an activist like her mother, but how did this upper middle class girl end up fighting for the working class specifically? Perhaps her friendship with Bert and the other chimney sweeps led to her learning about the not so magical aspects of their lives.
Wilkins may not just be a Morally Bankrupt Banker in attempting to seize the Banks' house. Remember that Michael made a ruckus about investing tuppence into the bank, hoping to donate it to "feed the birds" instead. This resulted in the bank suffering a significant loss as his outburst when the phrase "they're stealing my money" spread out like dominoes? He may be hoping to get back at him this way in particular.
Mary Poppins acts the proper English lady, speaking the Queen's English at all times, and always agrees reluctantly (or seems to) to any suggestion or idea placed before her, often with a deep sigh and an "oh, very well." When on stage, she can't help but cut loose into a bawdy Cabaret-style number, slip into a heavy Cockney accent, and agree enthusiastically to every idea. A Cover is Not the Book, indeed.
Speaking of that sequence, her accent change makes for a nice homage to English music halls of that day and age; much like the American Vaudeville, it was a place of lower class performers entertaining their kind. A cockney accent and a bawdy number, both usually associated with lower classes, are very appropriate considering all that.
Mr. Dawes Jr's claim that the Michael's tuppence had grown into a large enough sum to pay off the loan on his house seems... outlandish. His mention of "clever investments" seems to suggest the possibility that he's lying about the source of the money. Either he paid it off with his own money, or, being the guy who runs the bank, he decided to just forgive the loan with a cover story to let Michael save face. note On the other hand, given Michael's absent-mindedness where it comes to money, it also seems perfectly likely that he just doesn't know he's financially well-off.
Meta: some reviewers complained that the plot points in the movie were re-hashes of the same plot points in the original (animated sequence, visiting one of Mary's magical relatives, heartfelt lullaby sung in the nursery, etc.). However, this is pretty much exactly what P.L. Travers' first sequel Mary Poppins Comes Back did with regard to the original novel! Each chapter in the book directly corresponded with one in its predecessor: visiting one of Mary's relatives and finding out they have some kind of magical eccentricity (this was adapted, though altered for Mary Poppins Returns), one of the children is naughty and faces consequences for their actions (Bad Tuesday/Bad Wednesday), the baby of the family (the twins John and Barbara in the original, Annabelle in the sequel) speak to a starling (and his son in the sequel) about how babies understand things that are lost as they grow up (in the original, it's the language of animals, in the sequel, it's a mystic connection to the Universe), and so on. Disney wasn't being lazy in recycling plot ideas...in their own way, they were following the original creator's intent!
What does Mary Poppins do to the wolf and his associates after discovering his deception and attempts to harm the kids?
At the end of the movie, the Banks' house is redeemed. But then you'll realize on what will happen to the houses in London a few years after the film takes place, assuming their house survives. Worse yet, Michael is of age to be enlisted, and it's bad enough that his children have no mother and would have to evacuate. What happens if they have no father?
From a meta-standpoint, that we won't see Bert, George and Winifred Banks. Eventually they would pass on (and not of old age at that, since the movie happens some twenty years after the first one and they were not old at all in the first film, Admiral Boom is still around despite being much older than them), and not make it to see Michael's children.
The fact that George was likely one of the hundreds of thousands of British soldiers who went to France and never returned.
When Mary asks about Bert early on in the film, Jack mentions that he's traveling the world, hence why he's not involved with the film's events.
Unfortunately, more fridge horror in the fact that World War 2 is literally about to begin. Even if Michael is given deferment due to being a single father, his family is still right in the path of the oncoming bombings of London (unless they become Blitz Evacuees).
Mrs. Brill, Constable Jones, and Uncle Albert are absent from the movie, implying they too have passed away.
War I