How to Bury a Millionaire - S6-E7
Continuity mistake: In the scene where Martin is trying to find some aspirin and appears on the living room mezzanine, John Mahoney is wearing glasses (Martin wasn't wearing glasses at this point). In the next close-up shot the glasses have disappeared. (00:04:40)
How to Bury a Millionaire - S6-E7
Continuity mistake: When Martin is asleep reading a book, from one angle he is holding the book at the bottom and from another angle, at the top.
How to Bury a Millionaire - S6-E7
Continuity mistake: Frasier and Niles are at the Shangri-La, looking at an apartment for Niles. While they are standing in front of the closet, sometimes the door is open (revealing the former tenant's clothes inside) and sometimes it is shut.
How to Bury a Millionaire - S6-E7
Continuity mistake: Near the end of the show, Niles has signed his lease for the Shangra-La with his Noel Coward pen and he puts on the table next to the lease. A couple of shots later we can see the pen lying on top of the lease, even though no one touched it.
How to Bury a Millionaire - S6-E7
Continuity mistake: While Niles is talking to Marty on his phone/intercom at the Montana, the sherry glass on the table changes positions several 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.