Deliberate mistake: The background of the street scene from Frasier's apartment balcony shows cars and other vehicles but they are always standing still.
Continuity mistake: Frasier is based on the character originally created on Cheers. In Fraiser, he lives with his father who is a retired police man. On Cheers, Frasier once mentioned his father was a scientist. It's also worth noting that in one episode of Cheers, John Mahoney, who was to later play Frasier's dad, turns up as a pianist. Frasier also said on Cheers that his father was dead. When Ted Danson made a guest appearance on Frasier, Frasier admitted that he had lied about his father since the two had been arguing so much.
Continuity mistake: Across the show, Marty is supposed to be about 21 years older than Frasier (he turns 65 in season 5). There are at least two problems with his age - Frasier is supposed to have been born in March 1952 and in Season 5 (Roz and the Schnoz) Marty mentions going on shore leave as a single guy in 1952. Even if he was confused about the year, Frasier didn't call him on it. He must have done just a short stint in Korea as he was already a cop when he met Frasier's mother - they met at a murder scene, and he must have been 20 years old at the most. She was already a full fledged psychiatrist.
Revealing mistake: The elevator doors in Frasier's building are just a wood looking board with no safety edge sensors on the doors. These are required to detect an object between the doors. Yet, when a character touches the edge of the doors, they open back up.
Revealing mistake: The view from Frasier's apartment shows the Space Needle prominently in the background, however, the elevator that takes visitors from the ground to the observation deck is frozen in time midway to the top. This was corrected after the first season.
The Good Son - S1-E1
Continuity mistake: During the first episode of Frasier there is a painting of some vases in Frasier's apartment which is at the end of the hall leading on to Daphne's Room. In this episode the painting has a red and purple background, however in 'Here's Looking at You' (S1, 2 mins 52 secs) the exact same painting is now red and blue. It remains this new colour for the entire 11 seasons. (00:06:50)
The Good Son - S1-E1
Continuity mistake: In the scene where Daphne first comes to the apartment, the beer can and remote control on Martin's side table change positions between shots.
The Good Son - S1-E1
Continuity mistake: At the beginning of the show, when Roz is telling Frasier the mistakes he's made, the clock shows 4:52. However, after she says "you kept referring to Jerry.as Jeff", the clock is reading 4:50.
The Good Son - S1-E1
Continuity mistake: When Martin lies back in the chair for the first time, it changes how slanted it is in the first two shots.
The Good Son - S1-E1
Continuity mistake: Near the end of the show, when Roz is telling Frasier about Lupe Velez, the wall clock in her booth shows the time to be 3:45. About 5 minutes pass, although the story only takes a couple of minutes, and there is no other action in the scene. The clock actually goes backward after that, showing 3:50 and then about 3:48 in the next shot.
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.
Space Quest - S1-E2
Audio problem: Just before Frasier opens the door to get his paper, he says "I'll get him for this and his little dog too". However, his mouth moves when he says "I'll get him for this and his...", but his mouth doesn't move when he says "...little dog too". (00:02:40)
Space Quest - S1-E2
Continuity mistake: Frasier (and later the others) come back to his apartment to avoid the rain - they shake off umbrellas, and we even hear the storm at the very start of the scene. However there's no rain on the balcony - can't be covered, as we see in "Call Me Irresponsible" during the obligatory sex scene that when it's raining the balcony gets soaked.
Continuity mistake: When Frasier and Niles are eating the steaks at the restaurant that Martin brought them to, in some shots you can see Frasier's baked potato, and in others from the same angle it is not visible.
Continuity mistake: In the scene where Niles meets Daphne for the first time she is folding laundry and is holding a tee shirt that switches back and forth from being over her arm to being held in her fingers while they talk.
Continuity mistake: During the opening credits, Frasier is playing the piano and Martin is going through papers on the table. When Marty says "I don't know, Eddie, must you?" there is something pink lying on the table. The shot goes back to Eddie and then back to the table, but the pink item has disappeared.
Continuity mistake: While Martin is saying grace, Eddie is sitting right on his backside staring at Frasier, who yells "will you stop staring!" The next shot, from behind Eddie, shows him noticeably leaning over on one haunch, even though there was no time for the change.
Continuity mistake: Before they begin supper, Marty asks the boys if they still say a prayer before eating. His hands are clasped together in front of him, but in the next shot they are folded over each other.
Continuity mistake: While Daphne is making psychic predictions about Marty's murder case, there is a pencil lying under some photos. In one shot the pencil has disappeared but it reappears again in later shots. The angle stayed the same.
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.
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.