The Life Against Death Raid - S1-E2
Audio problem: The motorcycle/sidecar and jeeps' tyres sound like they're screeching on asphalt, when the vehicles are actually in deep sand.
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 Barney and Willy are digging their tunnel toward the prison basement, Barney's voice and lip movements are badly out of sync. (00:31:05)