Starring: Kelsey Grammer, David Hyde Pierce, John Mahoney, Jane Leeves, Peri Gilpin
Revealing mistake: When Frasier and his guest are standing up to leave, the girl behind the counter is watching them for her cue to come over.
Revealing mistake: Even though she has customers in front of her, the barista can be seen watching Frasier and his guest as they are talking, so she can see her cue to come over.
Visible crew/equipment: When Frasier is standing through his sunroof to speak with the drivers stuck behind him in the parking garage, one shot shows Frasier's body and much of the rear window which features a very clear reflection of the boom mic.
Selling Out - S1-E9
Frasier: Roger, at Cornell University they have an incredible piece of scientific equipment known as the Tunneling Electron Microscope. Now, this microscope is so powerful that by firing electrons you can actually see images of the atom, the infinitesimally minute building blocks of our universe. Roger, if I were using that microscope right now, I still wouldn't be able to locate my interest in your problem.
Chosen answer: The turkey's stuffing.