Continuity mistake: Season 5-9, Episode: My Half-Acre. While Cox and Carla are telling Mrs Wilk about her treatment, the cardigan she is wearing is completely unbuttoned. When the camera goes for a closeup of her face, the cardigan is now buttoned right up to her neck.
Continuity mistake: After J.D.and Julie take their picture with the old people masks and have taken them off, there are a lot of pieces from the mask still on their face. When J.D. has finished his small speech you can most of the bits from both of their faces has disappeared, with J.D's more noticeable than Julie's.