When Scrooge excitedly greets Mrs. Dilber, and dances with her, is he showing the same giddiness he was showing to everyone, or was he being passive-aggressive to the woman he now knows would happily loot his corpse.
One has to wonder how honest Belle was being when she leaves Scrooge in the past. She mentions that she's left dowerless by the death of her parents, but Scrooge hasn't broken it off with her. He actually tries to tell her that he would still love her - and maybe his desire for more money is motivated by the fact that she has no dowry - but she refuses to listen. Maybe her self-esteem is just so low that she has imagined that Scrooge feels this way.
The junior novelization takes Scrooge's line about wishing to speak to his clerk as him wanting to reconnect with Dick Wilkins, says Ignorance and Want are his Ignorance and Want specifically, and heavily implies the Ghost of Christmas Yet to Come nearly killed Scrooge as he fell into his grave.
Big-Lipped Alligator Moment: The Ghost Of Christmas Future chasing Scrooge around on a black coach. While showing off some nifty 3D effects and being genuinely spooky (and giving Jim Carrey a chance to adlib), it doesn't advance the plotline and isn't from the book.
The part where the Ghost of Christmas Present takes Scrooge on an aerial tour of Victorian London makes the already magnificent sounds of Hark! The Herald Angels Sing sung by a full professional choir even more epic.
Not to mention "God Bless Us Every One", performed by Andrea Bocelli.
Narm: The slow way of speaking Christmas Past uses can start sounding ridiculous after too long.
Signature Scene: The phenomenal scene of Scrooge being forced to bear witness to Bob's utter grief at losing his child, and knowing that it was his fault (albeit indirectly).
Squick: When Marley says Scrooge has a ponderous chain, ghostly spittle flies out. His jaw dislocating and cracking is also hard to watch, especially when his tongue flops out.
Jacob Marley's jaw dislocating, and his attempts to fix it, got criticism for being at a crucial point of his speech. He admonishes Scrooge that mankind was his business, but between his jaw clacking, his voice rasping, and bandaging his mouth shut, it's hard to understand him.
The part where Scrooge gets shrunk got a lot of criticism for not being in the book.
Uncanny Valley: The motion-capture and general animation style can make every character fall into this, but the Ghost of Christmas Past gets it the worst, especially when its face rapidly cycles between people Scrooge knows.
What Do You Mean, It's for Kids?: As a PG-rated Disney film, there are scenes that are especially freaky. Marley's ghost, the Ghost of Christmas Present's death, and Ignorance and Want are decidedly family-unfriendly, as is Christmas Yet To Come.