Continuity mistake: When Frasier and Roz are in the cafe talking about the See Bees, Roz says something like "Those shows are torture." When she does there are many different shots in a short space of time and if you're quick you can see the coffee mug suddenly jump into her hand without picking it up.David Mercier
Continuity mistake: Frasier meets Heather in the bar. She is reading a book which she has propped open on the bar, but as they talk, she takes it off the bar and closes it in her lap. A couple of shots later we see book is back on the bar and she is closing it again. (00:16:25)
Continuity mistake: Frasier is just saying goodbye to Niles and we can see the brochure for Daphne's reception to the left of his sherry glass. When he stands up and shouts "Daphne!" the brochure has moved about 6 inches to the right, even though no one touched it.
Continuity mistake: In the 8th episode of season 11, "Murder Most Maris", Frasier claims to have been "punched in the face yesterday by a man now dead". When he says this, two nights have passed since the murder. The next day Niles panics at the café and then sleeps for 20 hours. This time Frasier claims he was punched in the face three days ago by a man now dead, when by now it has been at least four days.
Continuity mistake: Roz comes back to the restaurant table, after phoning her babysitter, and says, "I have to go". At this point her purse is over her wrist. As she finishes saying, "Alice got a bead up her nose", she is holding the purse by its strap. A few shots later it is over her wrist again, even though she never moved it.