Continuity mistake: When Frazier comes into his booth to begin his show, Roz is reading a book. She says "Happy Birthday" to him and we can still see the book in front of her; but in the next shot it is lying on the console next to her, without any time for her to have put it there.
Factual error: This episode takes place on Frasier's birthday - Martin had ordered a copy of the newspaper published the day Frasier was born and it is sitting on the dining room table when Daphne glances at it and says "Queen Elizabeth's had another baby." - in the Episode The Late Dr. Crane earlier in the same season, Frasier was mistakenly reported as dead on a local TV news show. The dates for his life were shown on the show as 1952-1999. The Queen, in fact, did not have a baby in 1952.