Bushwhacked - S1-E2
Audio problem: When Zoë and Mal find the door to the cargo hold, Zoë checks to see if it's locked. Four beeping sounds can be heard as she does this, but she doesn't press any buttons. She only turns a knob on the door. The four beeping sounds are also heard before she even touches anything.
Audio problem: In the episode where the Wheezers obtain super powers, at the end of the episode, they are all singing their "Sitting and Singing" song surrounding the flaming duck. When the camera cuts to Carl putting his glasses on, the song can still be heard, but everyone's mouth just keeps saying "Standing, and standing, and standing," even though there are more words heard than just that.