Continuity mistake: Roz and Frasier are at Cafe Nervosa and she is telling him about her dream of dancing with Bruce Springsteen. At one point, her hand is on top of her coffee mug and then she lays it on the table; the next shot shows her hand on the cup again, with no time to move it naturally.
Continuity mistake: When Niles, Roz, Marty, and Daphne are in the living room confessing something shameful, Martin says, "Every time I watch 'The Sound of Music,' I cry." As the shot changes, we see that his hand goes from his arm rest to his lap and his beer can goes from being on one side of the remote to the other.
Continuity mistake: In the show from Series 7, "Big Crane on Campus", the Jean Smart character is introduced as Lorna Lenley - ex-prom queen from his high school with a volatile personality who has a brief relationship with Frasier. In Episode 21, series 8, she comes back as the same character - ex-prom queen, had a fling with Frasier, etc. - but now her name is Lana. She was billed as Lorna in the series 7 show and as Lana in the series 8 show. The names may be similar but are definitely different names.