Lights, camera, relationship - S6-E5
Revealing mistake: Right when the episode starts, a group of bystanders gather to stare at the filming.
Revealing mistake: When Sam and Jerry watch the billboard, a blue car passes by and the driver slows down and stares at the filming.
A woman's right to shoes (a.k.a. no shoes, no service) - S6-E9
Revealing mistake: When Charlotte and Carrie walk down the street there's a group of bystanders behind watching the filming. One of them is even taking pictures.
Answer: A popular brand of sexual lubricant. See http://www.k-y.com/index.jsp.
J I Cohen