Deliberate mistake: About halfway through the show, Roz and Daphne are in the kitchen talking. Daphne pours water into the teapot - but there is no steam coming from the kettle, nor any sound of a boiling/just boiled kettle. No self-respecting Brit would make tea with water that wasn't boiling.
Frasier (1993)
1 deliberate mistake in Frasier Loves Roz - chronological order
Starring: Kelsey Grammer, David Hyde Pierce, John Mahoney, Jane Leeves, Peri Gilpin
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.
Trivia: John Mahoney plays Kelsey Grammer's father in the series, even though in real life he's only 15 years older than Grammer.
More questions & answers from Frasier
Chosen answer: The turkey's stuffing.