Audio problem: 1897: Quentin challenges Barnabas by pulling a decorative sword from a wall display and pointing it at his throat. Unfortunately, the display wasn't all that well attached to the set wall. Though the camera pans away, you can hear a loud clunk as the piece falls, followed by the loud crash of shattering glass as it strikes and breaks a table lamp. You can also see the actors struggling very hard to keep straight faces as they continue with their lines.
Audio problem: When Jerry uses the elevator, the voice of the computer reads out the floors as "twenty-third floor, fourth floor, fifth floor" etc, missing out the "twenty-" prefix until the 29th floor. The DVD subtitles list these numbers with their prefix, so this was not intentional. (00:21:10)
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 Mac and co. enter the basement of the house in Queens (the one where the third woman was found) the record player lifts off its needle and moves to another spot on the record, cutting off the sound for a second. However, the music starts again slightly before the needle hits the record.
Audio problem: When Deb tells Angel to "look up" warning him of the security camera, Angel moves his lips as though he's talking but there is no audible dialogue. A few seconds later, his lips stop moving but then his audible lines are spoken. Then, again, there is no dialogue, but his lips move again. (00:07:15)