That Damn Balalaika!
In the early scenes, after Yuri's mother's funeral, Yuri is given his mother's red balalaika, which he claims not to be able play. All through the movie, not one of the characters play that balalaika, yet it is carried with them in the most difficult of circumstances. Yevgraf tells the family what to take when fleeing Moscow, and of all the essentials you might bring with you, why that balalaika?! When Tonya visits Lara before being exiled to Paris, one of the things she leaves for Yuri is that balalaika. Then, when Lara finally leaves Yuriatin with Victor on the train, she takes the balalaika with her. Yet no one plays the damn thing, ever!!
Oh, by the way, there's a balalaika goof that no one seems to have spotted: When Yuri gets to Lara's house after deserting from the partisans, she reveals the balalaika by drawing back a curtain under a table, and this action makes the strings resonate audibly. Yet, the balalaika has its neck wrapped in a blanket, which would muffle a sound like that!