Continuity mistake: In episode 64, "For Whom The Bell Tolls. And Tolls. And Tolls", Tracy is shown seated at the table with a bowl of cereal - but in the shots immediately before and after, she's not there, nor is there any food at her place. (00:01:10)
Continuity mistake: When the gang first arrive at the stately home Albert parks his car next to a coach. When the camera angle changes the car has moved back a few yards, and when the gang leave the car has changed position completely.
Firefly, Light My Fire - S1-E1
Continuity mistake: Joy exits her house twice: once after the curtains pull back, then a second time after Harmony says his line.