The Show Where Diane Comes Back - S3-E14
Revealing mistake: When the waitress brings Frasier his coffee, she tilts the cup quite a lot and you can see that it's empty. (00:13:00)
The Show Where Diane Comes Back - S3-E14
Continuity mistake: Frasier is in the kitchen and gets the sugar out to sprinkle over the profiteroles. As he starts shaking we get a wider shot and we see there is sugar all over the stove top, pastries, plate, and counter - way more than there should be for the amount of shaking going on.
The Show Where Diane Comes Back - S3-E14
Continuity mistake: Frasier, Martin, Niles, Daphne, and Diane are having dinner at Frasier's and he gets up to get dessert. Niles offers to help him and puts his table napkin in his chair. As he walks towards the kitchen, though, the napkin is lying next to his plate.
The Show Where Diane Comes Back - S3-E14
Continuity mistake: Diane is sitting in Frasier's apartment, at the dining room table, talking with him. Her hands are in her lap in one shot and then up in front of her in the next - in mid-sentence.
Chosen answer: The turkey's stuffing.