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.
Adaptation Displacement: Most people are aware that there's a book, but certain elements of the films are so ingrained in the audience's awareness of the story that it's quite a shock to go back and discover how different the original text is. Mostly striking is that Sara's father really does die in the book, that the Second Boer War isn't a backdrop, Sara was at Miss Michin's for at least ten years, and Becky isn't black.
She's also a Purity Sue and Sympathetic Sue. The book is about how everyone should feel sorry for the beautiful, intelligent, kind Sara who has been cast to the wolves of fate by the evil adults around her.
She does ostracize her friends after she loses her fortune, become unreasonably angry at Ermengarde for asking whether she was "very unhappy" on one occasion, and reflects that this outburst proves that at heart she is "not a nice girl".
She also gets away with her Suishness because the book is to some extent an examination of that very trope. Sara notes with internal cynicism the worshiping attitudes of everyone around her to her apparent perfection. She points out that she has been lucky to have been born into wealth, and has never had any reason to be anything but gracious. When she is tested by adversity graciousness does not come so easily to her. She struggles to remain patient with Ermengarde, to give most of her food to a hungrier child etc. It is only through a titanic exertion of her imagination and intelligence she is able to maintain the dignity, kindness and largesse she thinks of as 'princess' qualities
Notable is also that she is very close to breaking down a couple of times, especially towards the end of the book. Only unexpected moments of kindness help her to keep the bitterness at bay. In a way, she is only able to hold on her kindness because that is the only thing she has left. She might look like a beggar, but she refuses to feel like one. Thus making her kindness less an annoying character trait, but more something to cheer on, because it is the only weapon she has against Miss Minchin.
Crowning Moment of Funny: In the 1995 film, the entire scene of the girls stealing Sara's locket from Minchin's office. Lottie pretends to be crying so loudly that it distracts Amelia. After trying to quieten Lottie, Amelia runs down to the kitchen to get Sara (because she can calm Lottie down). By the time they get back upstairs, the girls have the locket and Lottie cheerfully walks past Amelia and Sara. Additionally Minchin comes back early and opens the door to her office, so Becky screams to distract her. Becky stutters for a few seconds while the rest of the girls clear out of the door before saying "I thought I saw a mouse". Minchin rolls her eyes and turns to walk into her office, bumping into the door (which had been closed by Ermengarde).
Fridge Brilliance: Lavinia becoming paranoid about her hair falling out in the 1995 film. She's used to the other girls brushing it for her so she likely has no idea that stray hairs are going to come off. But at the time Sara 'curses' her, all her Girl Posse has grown sick of her and she must brush her hair by herself.
Nightmare Fuel: The film adaptation adds a great big grizzly Hydra thing made out of thorns.
From the original book, Sara's fate at the hands of Miss Minchin. There's no clear explanation as to why Miss Minchin has always resented the little girl so much, and Sara had no clue she hated her until her father dies and Miss Minchin no longer has to treat her like a parlor boarder anymore. (She had sensed earlier, however, that Miss Minchin fawned on her mainly because she was rich). Miss Minchin is definitely one of the cruelest Sadist Teachers in fiction.
Actually, there are three explanations for Miss Minchin's hate. One is the below mentioned scene when Sara unwittingly embarrasses her, in which is explicitly stated that this was the moment resentment started. The second is stated towards the very end, when her sister says that she couldn't stand the fact that Sara saw through her from the very beginning, suggesting that Miss Minchin felt inferior to her, even when she lost everything. The third is more substantial: Miss Minchin thought that Sara would be the key to a lot of money. Instead she ended up with a lot of debts.
Miss Minchin seems to resent Sara's precocious self possession, intelligence and ability to read people, even adults. She never forgives Sara for unintentionally embarrassing when she insists Sara study French and it turns out Sara is already fluent in the language.
One of the adaptations turns the question of resentment into a bit of a Tear Jerker by implying that her father wasn't nearly as kind to her as Sara's was. Still, the scene in that same adaptation, in which we see Sara's father in the war zone, with all of the dead around him, is plenty scary.
Tear Jerker: It's amazing how heart-wrenching four simple little words can be. "I shall die presently."
The 1995 movie's climax counts as a tearjerker as well.
To say nothing of Sara's first night in the attic. the book tells us it cannot possibly relate what Sara goes through. The movie shows us a broken little girl, crying for her papa in a chalk-drawn circle of protection all alone *sniffsniff*
They Wasted a Perfectly Good Plot: almost all the adaptations have this with regards to Sara's redecorated room. In the book, Mr Carrisford and Ram Dass secretly decorate Sara's quaters and leave her things like hot food at meal-times and warm blankets, and a fire in the grate. Most films (the 1917, the 1939 and the 1995 amongst others) have Miss Minchin discover this, assume that Sara and Becky have stolen the finery, and this event prompts the climax of the story. In the book Miss Minchin never sees the room.
Values Dissonance: several minor details that seem odd, like the greenishness of Sara's eyes being some kind of huge obstacle to her ever being considered a traditional beauty.
Sara "sees herself as ugly" because — with her slender build, short dark hair, green eyes, and olive skin — she does not in any way match the Victorian-Edwardian image of child beauty; she compares herself to another child in her father's regiment, who has "dimples and rose-colored cheeks, and long hair the color of gold." Black hair was also not a good hair color to have in 19th-Century British India — as it suggested Sara (or her mother) might be mixed-race. Also at various points we get mentions of Sara's "brown" hand and "small dark face".
The situation involving Becky coming along as Sara's maid may be due to the fact that, as a lower-class member, Becky doesn't have the education to gain other employment or respectability in her era.