Ain't Nobody's Business If I Do - S5-E11
Continuity mistake: Niles and Frasier are looking at the file the detective made on Sherry. In one shot Niles has papers in both hands but in the next shot he only has them in one hand, and there was no time for him to change.
Ain't Nobody's Business If I Do - S5-E11
Continuity mistake: Frasier, Niles, Martin, and Daphne are in the living room talking about people who have been married multiple times - in one shot Daphne is looking forward but in the next she is looking backwards at Frasier.
Ain't Nobody's Business If I Do - S5-E11
Continuity mistake: Frasier and Niles are looking at the report the private detective gave them on Sherry - Niles is holding one sheet apart from the others but as he says "it does bode well for Dad", the papers are all together again, with no real time for this to occur.
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.