Audio problem: During Beca's performance of Freedom, she is singing with Cynthia Rose. During the little chorus pre-verse (before they put their hands in the middle), you can hear Beca's voice singing the lyrics but Anna Kendrick's microphone is nowhere near her mouth. Her lips don't even match it.
Audio problem: Whenever Tonya skates, you can hear the sound of figure skate blades scraping at the ice. Not only do they not correspond to the moves being made, but a skater of that calibre, not to mention of her technical prowess, simply wouldn't make those sounds at all.
Audio problem: During "This is me", when they enter the room and get to the "oooh oh oh" part if you watch the albino the sync is out as their mouths open after the music has ended on that part.