Audio problem: When singing "Goodbye little yellow bird" Emma blows a kiss to Oliver offstage, but she is still singing the song when she is blowing the kiss. Although it's possible she was pretending as it was part of the act, her voice wasn't even muffled by her hand.
Audio problem: When Gina shoots Nico Arroyo at the end of the episode, she fires twice but only one shot is heard.
Another Song for Christmas - S1-E13
Audio problem: At the very beginning the audio track of the outside noise at the dealership seems to have been laid wrong. It runs into the next interior shot and abruptly stops.