Continuity mistake: When Frasier and Marty are talking about going to Ronee's cabin, Ronee is sitting on the right side of the couch with nothing behind her. In the next shot, she gets up and we can see a light brown overcoat. This coat disappears again in the next shot, as Frasier answers the door and Niles comes in, carrying the very same overcoat which he places on the right side of the couch, where Ronee had been sitting.
Continuity mistake: During the opening credits of the show, Frasier and Roz are in Cafe Nervosa. Frasier has a fabric shopping bag, and in some shots you can see the leaves of one vegetable and in other shots you can see the leaves of two vegetables. These leaves are quite large and distinctively different.
Goodnight, Seattle (1) - S11-E23
Continuity mistake: When Daphne, Niles, and the vet are in the examining room the items on the table in the foreground change positions in different shots.
Continuity mistake: Frasier is hiding behind the kitchen counter when Ronee comes in - followed by Marty. Frasier puts his hands, one holding an apple, up on the counter. In the next shot the apple is on the counter, and his hands are draped over each other - without enough time for natural movement.
Continuity mistake: There are several bad cuts between shots when Niles and Frasier are on the balcony. Keep an eye on the height of Niles' sherry glass. The most noticeable occurrence is when Niles mentions "detachment" and the shot changes. He is suddenly holding his glass at least a foot higher in the air.
Goodnight, Seattle: Part 1 - S11-E23
Visible crew/equipment: (This is for the last episode, "Goodnight, Seattle.") When Kenny opens the door to use Frasier's bathroom, you can see a light pass across the wall above the fireplace.
Revealing mistake: At Cafe Nervosa, after Niles has had a mini-breakdown, he has shed his clothes, boxers and all, all over the place and is supposedly naked in the corner with only a newspaper for privacy. When Frasier has him stand up to wrap aprons around him, one can see that David Hyde Pierce is actually wearing light-coloured briefs.
Continuity mistake: In an early scene, Frasier is in his apt. talking to Marty about how Niles is behaving. The cracker package on the table changes position noticeably without Frasier having touched it.
A Man, a Plan and a Gal: Julia - S11-E2
Continuity mistake: As Frasier is protesting his love for Julia and says "the essence of music", Daphne's hands go from being on the couch to being folded on her knees, without enough time to do it in real time.
Continuity mistake: When Martin and Frasier are in Cafe Nervosa and Marty is lecturing his son about eavesdropping, his newspaper moves a few inches, from being on his left to being right in front of him, even though he never touched it.
Revealing mistake: During the scene where Frasier is dropping Charlotte off at the train station (the first time) you can see the background behind him shows that the car they are in is turning left. Yet we can see his hands on the top of the steering wheel and during this time he never turns the steering wheel.
Boo! (a.k.a. I'm With Her) - S11-E16
Continuity mistake: Marty is home from the hospital and there is a basket of flowers on the coffee table. The basket moves several inches to the left while Niles goes to the door to let Ronee in.
Goodnight, Seattle: Part 2 - S11-E24
Character mistake: Frasier says, "it's only an hour flight to San Francisco..." Seattle to San Fransisco is two hours minimum.
Continuity mistake: After Frasier watches the video of Eddie, he tosses the remote on the coffee table. When Niles comes in a short time later, the remote has disappeared, but when Niles asks, "Aren't you going to ask me what's up?" we can see the remote again, on top of the manila envelope. It disappears and reappears throughout the scene.
Continuity mistake: During the opening credits, Roz and Ann are sitting in Cafe Nervosa - just before Roz says "Frazier" we see Ann put her mug down. When Frasier approaches, we see her put it down again.
Continuity mistake: When Roz is talking to Martin in the cafe, she takes a cookie from the plate, but in the next shot she gives the brownie to Martin with the same hand and the cookie is nowhere to be seen.
The Ann Who Came to Dinner - S11-E13
Continuity mistake: Maris is hiding in a wooden box so she will be shipped out of the country. Marta, her housekeeper, has a protein shake for her, and puts the straw through a hole in the box. Maris indicates that she's drunk too much and Marta goes to put the straw back in the hole so she can regurgitate some - but just before that happens we see a stream of the liquid come out of the hole and dribble down the box. In the next shot the straw goes into the hole and the box is all clean and dry again.
Continuity mistake: Daphne comes into the Cafe and asks Marty, "Where have you been?" and her purse is on her right shoulder. In the next shot her purse is in her hand, but not enough time had passed for this to happen naturally.
Continuity mistake: At the end of 3-10 in the airport with Kate, Frasier says that he has an allergic reaction to cats but here he cat sits for Mr. Bottomsly.
Suggested correction: This has been addressed in the Questions section. Frasier is apparently choosing to deal with his allergies, in order help the cat's owner. It's also possible for allergies to be triggered by one cat, but not another. It depends on the amount of dander that the particular cat produces, and the level of Fel D. 1, a protein in their saliva.
Character mistake: Frasier tells Niles that the article on him will be in the winter/spring issue of Seattle Broadcaster. The man who interviews him introduces himself as a journalist from the Seattle Times.