Continuity mistake: When Meredith's talking to Lexie in the clinic, in one shot from Lexie's right there's a chunk of hair hanging in front of her ear. We cut to a shot from the other side, then back, and without her touching it, it's now neatly tucked back.
The Heart of the Matter - S4-E4
Character mistake: Ms. Bitzer says she's booked a trip to Iceland to experience the sun never setting. While the sun does set quite late there, Iceland is located south of the polar circle and does not have midnight sun. And either way, season four has been established as taking place after summer, so there wouldn't be midnight sun anywhere.
Revealing mistake: When Ray is panicking over being in the rig with his dead partner, Stan, and turns to look at Meredith, you can see Stan's eyelashes flutter as he blinks. (00:36:37)
