You Can't Tell a Crook by His Cover - S1-E15
Continuity mistake: When Frasier and Niles are in the cafe talking about the Topaz Room, the waiter goes from bending over the table to collect the money to upright a few feet from the table instantly.
A Midwinter Night's Dream - S1-E17
Continuity mistake: The time on Niles' musical clock changes time suddenly and frequently between shots, once from 9.00 to 10.55 to 11.25 almost instantly.
You Can't Tell a Crook by His Cover - S1-E15
Continuity mistake: When the doorbell rings Martin leans over to put the cards down, you see him do it twice.
Continuity mistake: The pickle being eaten by Bulldog after he enters Frasier's apartment and sits down on his couch gets bigger after Bulldog takes a bite out of it.
Miracle on Third or Fourth Street - S1-E12
Continuity mistake: When Roz and Frasier are exchanging gifts, Roz takes her present out of its box and the box is still at least half covered in wrapping paper. In the next shot, no wrapping paper is visible around the box.
Deliberate mistake: In the pilot episode, "The Good Son," Frasier has a telescope which is seen on his balcony. The telescope disappears for the next 3 episodes but in Ep. 5, Frasier gives his father a telescope as a gift. It remains as a prop for many seasons.
Continuity mistake: As Catherine is about to leave Frasier's apartment near the end of the episode, you can see the white shirt she is wearing constantly changes between shots. At times it is hanging out very loosely and in other shots it is neatly tucked in and positioned to the right.
You Can't Tell a Crook by His Cover - S1-E15
Continuity mistake: When Linda opens her beer, her three piles of poker chips are arranged in a triangle. In the next shot, they are laid out in a line, but she has not moved them.
The Good Son - S1-E1
Continuity mistake: When Daphne first arrives at the apartment and is complimenting Martin's chair, his plate moves around on the side table between shots.
Selling Out - S1-E9
Continuity mistake: Frasier meets Bebe for the first time in the hall at KACL. She has her business card in her hand for part of the scene but after Frasier tells her he has a son, the card disappears - with no time for Bebe to have put it back in her purse.
Continuity mistake: At the radio station, Roz waves her pencil at Frasier through the glass to wrap up his show; she has a KACL mug in her other hand. The next shot shows her actually leaning over to pick up the mug, without enough time for her to have put it down in the first place.
Miracle on Third or Fourth Street - S1-E12
Continuity mistake: When Roz and Frasier are exchanging gifts, when Frasier first puts the lid back on the gift box there is no tissue paper sticking out. In the next shot, a large sheet of red tissue paper is outside the box.
Continuity mistake: When Daphne is setting up the soft ornaments along the top of the fireplace for the Christmas photo, she is just putting the first one on the mantelpiece, then the shot changes and she is positioning the second ornament.
Miracle on Third or Fourth Street - S1-E12
Continuity mistake: When Bulldog is trying to persuade Frasier to cover his shift on Christmas Day, Bulldog's cup of eggnog jumps back and forth from sitting on the desk to in his hand.
A Midwinter Night's Dream - S1-E17
Continuity mistake: Early in the show Niles shows up at Frasier's in his pirate outfit. He has a plastic knife in his sash which changes position noticeably several times during the scene (without Niles touching it).
Continuity mistake: As Frasier and Niles are starting work on their book, Marty gets four snacks and a beer and sits down in his chair. He gets up and we see the two bags that were behind the beer and can of something are now in front of them. Marty never touched them during that time.
Selling Out - S1-E9
Continuity mistake: When Frasier and Niles are in the Cafe, Niles says something like "Why do you feel like that?" During this line Niles goes from putting sugar in his coffee to having the mug raised instantly.
Continuity mistake: When Katherine confronts Frasier in the hall at KACL, her purse strap is over her forearm. But when the shot goes to Frasier, from behind her, the strap is over her shoulder.
A Midwinter Night's Dream - S1-E17
Plot hole: Niles phones Frasier to tell him Daphne is staying at his place because of the storm. Frasier's phone is in its usual place on the room divider/bookcase behind Marty's chair. After Frasier and Marty leave to rescue Daphne, Niles phones again and Eddie is standing up on a chair staring at the phone. Only problem is, the phone is over on Frasier's desk, where there normally is no phone. If he did have a phone there, it is only a few feet from the other one, which makes no sense.
And the Whimper is... - S1-E18
Continuity mistake: Early in the show, Frasier is sitting in Cafe Nervosa with Niles and Bebe, drumming on the table with the fingers of his left hand. In the next shot his hand is pulled in, lying on the table in front of him.
Answer: It equals the record of James Arness of "Gunsmoke" for the actor who's played the same part on TV NOT in a soap opera. If you include soaps there are two main contenders - William Roache, who's been playing Ken Barlow in "Coronation Street" in the UK since 1960. Don Hastings has been playing Robert Hughes in US soap "As the World Turns" since 1960 as well.