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.
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.
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.