Before running into Friedrich on the street, the hem of Jo's dress is soaked in mud. Afterward, in his apartment, it is clean.
When Laurie spots Amy painting in Europe, he drops his
cigarette twice.
While walking to school, Amy drops her chalkboard, then picks it up twice.
The soldiers' uniforms in the various party scenes have both stripes on the sleeves and shoulder boards. In reality, stripes on the sleeves denote an enlisted man, and shoulder boards denote an officer. They are thus mutually exclusive and both would not have been worn by the same individual.
When Teddy and Jo are packing up his books to take to Harvard, she hands him Dickens's "Dombey and Son"...but Jo incorrectly calls the book, Dombey and Sons - which is incorrect.
When Amy discovers that Jo will be her teacher, she sulks twice. However, this is in keeping with Amy's character - if no one noticed her sulking the first time, she would most likely do it again.
The carol 'Ding Dong Merrily On High' was first published in 1924 with lyrics by George Ratcliffe Woodward.
Where Marmee withdraws Amy from the school, Amy is shown eating what are clearly fresh-baked chocolate chip cookies, a confection not invented until 1930.
The opera which Jo and Frederick watch is Georges Bizet's "Pearl Fishers", which was first performed in Paris in 1863. However, the opera was not performed in the U.S. until 1892, long after the action of the film.
The lyrics to the carol 'Deck The Halls' as sung in the movie are a variation of the original English lyrics and were first printed as this variant in America in 1877, although without the third 'fa la la la la...'.
In the final scene, Prof. Bhaer's umbrella has a modern spring clasp.
When looking at Laurie through the window, Jo wonders if he is a captive, "like Smee in Nicholas Nickelby". The character she is referring to, however, is called 'Smike'.
Actresses Kirsten Dunst and Samantha Mathis do not look enough alike to play the same character, Amy March.