Continuity mistake: Marty is telling the boys that he doesn't want to get involved in their squabble. Frasier has his hand up in the air holding his address book but in the next shot it is down by his side, with no time to change position naturally. (00:06:05)
Continuity mistake: In the opening scene, Frasier is having coffee with Nancy and Roz comes in - she sits down and goes to put her purse on the floor. In the next shot her arms are suddenly up on her table and her hands near her face - without enough time for this to have happened in real time.
Continuity mistake: Frasier gets out his address book to look for women he's dated but we can see the pages are blank even while he reads out names. He is not making them up, as he does phone one named Tatiana later.
Continuity mistake: At the end of the show, when Martin, Niles, and Frasier are leaving Niles's place to go out for ice cream, they leave Maris's opened package on a large footstool next to a decorative metal bowl. When they return (closing credits) with their ice cream the package and its wrappings are gone - even though no one was left behind in the apartment.
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.