These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Is Cratchit really the hard-working, underpaid Woobie that everyone thinks he is or is he really just such a lousy bookkeeper with absolutely no productivity on the job and has such a huge lack of skills that absolutely no one would hire him to the point where Scrooge did so out of mercy? Businessmen want to hire skilled workers and pay them what they're worth. If Cratchit really had the necessary skills he could have, you know, found the same job under another employer. Not to mention he already had a few kids who were capable of working.
Except, if what Marley showed Scrooge was any indication, most of the other employers paid as little as Scrooge did! So, trying to find the same job under another employer would present a number of new difficulties (at least temporary unemployment which, in those times, could be deadly) as well as the possibility that, without The Internet, Cratchit would have a much more difficult time finding a similar job at all - let alone one that pays better. As for his kids, they may very well be working, for all we know. Often, even that wasn't enough during those times.
At least two of the Cratchit children are working. The eldest daughter Martha works at some kind of mill or textile factory, and the eldest son Peter is or soon will have a "situation" that Bob is trying to arrange.
Furthermore, at the time it was nearly impossible to advance in a career without recommendations from a previous employer, and they had full right to refuse for any reason they saw fit. How likely would it be for Scrooge to give any recommendations to a man who, from his point of view, leaves his employment for sheer greed?
Is Scrooge really the uncaring miser that everyone paints him out to be or is he just a skilled businessman who is the only one with enough mercy to hire an unskilled louse like Cratchit and paying him what he deserves while deciding what he wants to do with his own money despite the entire city trying to steal it from him in a wealth redistribution scheme? The story isn't about redeeming Scrooge; it's about getting into his wallet.
Of course, he does exactly jack-shit with his money, keeping it all to himself and suffering (emotionally) just about as much as everyone else, but by his own hand, for it. In fact, by not buying more things, he deliberately keeps his money out of the economy and makes it more difficult for others to get jobs. The "wealth redistribution scheme" is simple charity. The concept of charity is based on an honest acknowledgement that, whatever "skill" Scrooge used to get ahold of his wealth, he also needed a little bit of luck as well. Luck, which not everyone is fortunate enough to have and those less fortunate do deserve to live, despite what some people may say.
Also, by hoarding his money and not spending or giving it away, Scrooge is actively destroying himself with his own money. A miser doesn't even love himself. The charity the spirits instructed him in wasn't so much about the recipients as much as it was about curing Scrooge of his idolatry
Also the Ghosts in general, is the Past another Good Is Not Nice spirit trying to teach Scrooge about his past, or a Jerkass who really loves to exploit the flaws of Scrooge's past and in some versions show what he could've had if he was not greedy; pushing him away from loving Christmas due to regret, and enjoy it as he/she/it invaded his mind. Tends to depend on the adaptation though, as some versions of ghosts seem more benevolent than others.
Anvilicious: But good! (Apparently Dickens even considered "The Sledgehammer" as a title.)
While the moral of charity and giving is obvious, more specifically, the novella was meant as a Take That to Thomas Malthus, whose warnings of overpopulation resulted in laws that Dickens hated because he felt they hurt the poor.
Magnificent Bastard: Scrooge and Marley earn this in the 1951 version. They offer to bail the Mercantile Association out of the debt caused by Jorkin's embezzlement, provided they'll be allowed to buy up 51% of the total stock. They'll only save the company if they can become the company, and both look really pleased about it.
Moral Event Horizon: The three spirits make Scrooge himself go through his past to realize how far his actions have gone.
Nightmare Fuel: Really, anything to do with Marley. He's not exactly a comforting sight to begin with, wrapped in chains and pretty dead-looking as he is; he visits Scrooge in frankly terrifying circumstances, scares the crap out of him, and tells him about the horrific fate in store, which he is already suffering.
Strawman Has a Point: Scrooge's comments about the workhouse may seem very harsh, but the workhouse was intended to be a really bleak place and a last resort, not a place that was nice to be.
The Ghost of Christmas Past in particular tends to get hit with this. This could be because the description in the book is extremely difficult to depict visually; the first paragraph of the description is fairly doable, but the second paragraph...
"... its belt sparkled and glittered now in one part and now in another, and what was light one instant, at another time was dark, so the figure itself fluctuated in its distinctness: being now a thing with one arm, now with one leg, now with twenty legs, now a pair of legs without a head, now a head without a body: of which dissolving parts, no outline would be visible in the dense gloom wherein they melted away. And in the very wonder of this, it would be itself again; distinct and clear as ever."
Uncanny Valley: The land from whence Mr. Zemeckis draws his CGI characters.
There was some improvement over his previous efforts (The Polar Express in particular), but he did tend to re-use faces for several characters (compare Fezziwig and Bob Cratchitt), and in one scene (in the future, where the Cratchitts are mourning Tiny Tim) the eldest son's face freezes after he's done with his lines.
Values Resonance: Part of the reason why this story continues to be adapted to this very day.
What the Hell, Casting Agency?: This blogger points out that pretty much every version of the story that gets told with existing characters has one in-story character that there's no good fit for, and one actor-character that there's no good role for, so they just squish them together.