Fair for Its Day: Jean Webster was an early-20th century feminist, and it shows, particularly when Judy and Sallie talk about voting — which women could not do at the time that the two books were published.
Judy and the Semples' discussion about God. For the sanity of both parties, they decide not to bring him up again.
Judy saying Julia's family evolved from the most intelligent monkeys with "fine, silky coats."
Judy wondering if you would either float or sink if a pool was full of gelatin
From the musical, Jervis saying his low expectations of his family come from Julia of all people.
Germans Love David Hasselhoff: The novel is popular in Japan enough to spawn an two anime versions, as well as one of Japan's longest charities, The Foundation for Orphans from Automobile Accidents, is also nicknamed the "Daddy-Long-Legs Fund".
Values Dissonance: A given considering the age of the novel - however, it is particularly noticeable at one point in the sequel when Sallie uses a pancake turner to beat the hell out of a boy. Made worse by the fact that more people were concerned about Sallie's nerves than the boy's limp. To be fair, the boy had been torturing a mouse and the already very stressed Sallie simply splintered when she found out.
The parts where she describes deaf, epileptic, and intellectually challenged children as 'defective' and needing to be shut up in institutions so they don't pollute society also make the modern reader wince.
Allegra's potential adoptive father seems to treat her like a sort of "pet" to give as a gift to his Ill Girl wife, rather than an actual child with her own thoughts. It shows a lot when Sallie refuses to give Allegra away (because the girl has two older brothers and he doesn't want to adopt them), then the gentleman throws what can be easily seen as an Upper-Class Twit tantrum and blames Sallie for it. Thankfully, he re-thinks his attitude some time later and takes all three children home with him.
An odd example in the original novel; Judy mentions that, after spending her first summer at Lock Willow Farm, she gained almost ten pounds and recommends it to Daddy as a health resort. In her case, however, it could be an illustration of having been incredibly underfed at the orphanage.
Ugly Cute: Harvestman is a giant fat arachnid with very little hair who is also utterly adorable.
The Woobie: Scapegrace has shades of this at times, with his extremely sad and depressing dreams, which indicate his childhood was not exactly nice and his family was dysfunctional and screwed up. Oh and he's probably having the same sickness his dad had, showing the same symptoms, so there's the possibility that his days are numbered. And really, Harvestman and Crane are pretty much his only friends, and even Crane thinks him to suspicious and creepy, such as the scene where he immediately thought Scapegrace to be the cause of his missing son. It's hard not to feel sorry for him.