Continuity mistake: Niles comes into Cafe Nervosa and Marty has his hands down in this lap. Niles says "not interrupting anything personal, am I?" the shot goes back to Marty, whose arms are now folded.
Continuity mistake: Marty is in Cafe Nervosa and Roz comes in; he puts his newspaper aside. The next shot shows his hand is still on the paper; this time the page is different. Through the scene we sometimes see a page of text and sometimes a page of ads.
Continuity mistake: Frasier comes home to his apartment with a bottle of wine in a paper bag. He takes the bottle out and puts it on the table holding the bag in the other hand, but in the next shot we see the bag is already on the table and he is just placing the bottle down.
Continuity mistake: Marty, Frasier, Niles, and Daphne are in Frasier's apartment, talking about Marty moving in with Niles - M.'s beer can and remote are sitting on his little table. In one shot they are quite close together, but in the next the can has moved about six inches forward.
Audio problem: As Frasier walks into Niles' kitchen, Daphne is on the phone, talking. We hear a hoarse sound, like Frasier's voice, saying "Daph" or "Dad" but it makes no sense as she is on the phone talking to someone, and he is heading for the fridge. When she hangs up, she and Frasier start talking about her employment situation.
Continuity mistake: While Niles and Frasier are discussing Marty, we can see an old shoe on the footstool, but as the shot changes the shoe is gone and there is a newspaper there instead.
Continuity mistake: Eddie has been playing on Niles' couch, and the pillows are all over the place and there are a couple of other things on there as well. After Marty's chair arrives, Niles says to Frasier, "You have to take him back now," and suddenly the couch is all tidied up, with the pillows at the ends. A couple of shots go by and suddenly the couch is a mess again.
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.