Continuity mistake: When Carrie and Shaun are laying on the floor of her bedroom, she has her left hand resting on her chest. But in the very next shot; her left arm is laying across her stomach, and her left hand is curved around her right waist. No time has passed in between these shots. (00:12:25)
Continuity mistake: During this scene when Samantha is confronting her new assistant, the office set-up is completely different than before, when Nina G. was working for her. The assistant office space is much larger, glass desk, different angle, next to small conference room instead of Samantha's office, etc.; obviously not the same office set as previously used. Yet Samantha has not changed offices at all during this time period, as it wasn't too long ago when she fired Nina G. Something as major as changing offices would definitely have been mentioned in the plot (as changing apartments always is); and there hasn't been enough time since she fired Nina G. (00:13:45)
Suggested correction: You're assuming that moving to a new office must be a plot for a new episode, which makes no sense (plus, it's a show that revolves around sex, women, restaurants and bars). Furthermore, the episode you mention is S2E17. Many months have passed and it's perfectly plausible for Sam to move some place else.
Continuity mistake: After spilling the sauce on the floor, when Miranda is discussing with her boyfriend her bag suddenly disappears from her shoulder. Later on it magically appears on the floor.
Continuity mistake: When Miranda drops the paper bags on the floor a lettuce and a bottle of water fall out. Seconds later the stuff changes completely: The bottle is gone, the bags are in a different position and, best of all, Miranda's leather bag (which was previously hanging on her shoulder and suddenly disappeared between shots -listed mistake-) magically reappears on top of the mess.
Continuity mistake: When the tomato jar crashes on the floor, the splatter changes shapes between shots and the label disappears in the second shot.
Continuity mistake: Baird puts a sock inside Charlotte's crotch and her tie gets skewed. A shot later it's straight.
Continuity mistake: During the exhibit, when Baird shows up, a group of people suddenly appear behind him and Charlotte.
Continuity mistake: While in the exhibit, Stanford is behind Carrie, but a shot later he is standing next to her.
Continuity mistake: During breakfast Carrie says "they all ended up with men", and Sam's coffee mug is on the table. Half a second later, she already has the mug next to her face.
