The length of the chain for Beth's cross necklace changes throughout the film, from choker length to reaching beyond her collarbone.
Papa March is seen in his Army Battle Dress Uniform (BDU) with rank insignia (captain's "railroad tracks") on both collars. Army officers did not wear rank insignia on both collars of the BDU but rank insignia on the right collar and branch insignia on the left collar; as he has been identified as a surgeon, he would have worn railroad tracks on the right and the caduceus insignia of the Medical Corps on the left. (This is still not nearly as bad a goof as in the 1994 version Little Women (1994), set during the Civil War as was the original novel, where every other soldier seen in uniform beside Papa March wore both officers' shoulder boards and enlisted men's stripes!)