Continuity mistake: After the drinks night, Carrie and Berger start to kiss. He is on top of her and she places her hand on his chest. A shot later it's around his neck. (00:02:35 - 00:24:39)
Continuity mistake: When Sam asks the clerk for specific lingerie, the dress is close to her and she touches it with a her right hand. From the opposite angle her arm is lowered and her left arm holds the dress away from her. (00:13:35)
Continuity mistake: When Berger tells Carrie they must make the bed, her left arm is next to her body. A shot later it's stretched out.
Continuity mistake: Carrie and Berger wake up and he says "We're the couple you wanna be" and her legs are stretched out. A shot later they're bent under her bum.
Continuity mistake: When Carrie wakes up with Berger, her hair covers half of her face and is neatly brushed. From a wide angle it doesn't and it's quite messy.
Continuity mistake: When the lingerie clerk shows the blue dress she holds the clothes hanger from the middle part. From the opposite angle she is holding it from the side.
Continuity mistake: When Sam and Carrie go to the lingerie store, Sam raises her right arm to touch a blue dress. From the opposite shot her arm is lowered.
Continuity mistake: Miranda's pizza is sometimes stiff, others really fluffy, other so-so. Also, the size of the bite changes between shots.
Continuity mistake: While eating a burger, Berger wipes off food from Carrie's mouth and the ketchup bottle magically disappears from the table.
Continuity mistake: While the girls wait for their table, check the apple on Sam's cocktail and you'll notice that the glass' position is inconsistent between shots.
Continuity mistake: Right when the episode starts Carrie is grabbing a long piece of melted cheese that stretches out of her burger into her mouth. Half a second later the burger and cheese have vanished. And her arm is lowered.
Answer: A popular brand of sexual lubricant. See http://www.k-y.com/index.jsp.
J I Cohen