Continuity mistake: When Grace reads Dr. Morty's letter on Karen's boat (in the last episode of season 5) it sounds at least a few paragraphs in length. During this episode, when she holds the letter up there is only a short paragraph on the bordered side of the page, and nothing on the back side.
Continuity mistake: As Leo speaks with Diane (he's on the sofa; she's in a chair) she refills her wine glass until it is nearly full. In the next shot Diane takes the last sip of wine from her glass, and the following shot shows her glass nearly full again.
Continuity mistake: After Grace pours Jack some eggnog, we see the pitcher on the desk, and no eggnog is visible. It then shows Karen getting out her laptop, then back to a shot of Grace looking stunned, and now the level of eggnog in the pitcher has almost doubled.
Continuity mistake: When Grace and Karen enter the cabin, Grace puts her bag down on top of the sofa, so that the large bottom faces the door. In the next shot when she walks back over the bag has now changed position so that the bottom of the bag faces us.
Continuity mistake: When Dr. Hershberg is crying after giving some bad news, he knocks a grey box off of the small equipment table which he is leaning on. Later during the scene the box suddenly jumps back up onto the table. Also, the other items on the table jump around and change position on their own accord a few times.