Fool Me Once, Shame on You, Fool Me Twice... - S2-E14
Continuity mistake: Frasier meets Heather in the bar. She is reading a book which she has propped open on the bar, but as they talk, she takes it off the bar and closes it in her lap. A couple of shots later we see book is back on the bar and she is closing it again. (00:16:25)

Fool Me Once, Shame on You, Fool Me Twice... - S2-E14
Continuity mistake: In Cafe Nervosa, Frasier has just checked the priest's briefcase, think its his own. In one shot his hands are down by his side but in the next split second his left hand is up at his neck and then patting his tie.
Fool Me Once, Shame on You, Fool Me Twice... - S2-E14
Continuity mistake: When Daphne is telling her story about living in London, the towel on top of the laundry basket changes from being red to being blue, without her rearranging it. (00:06:15)
Fool Me Once, Shame on You, Fool Me Twice... - S2-E14
Continuity mistake: Daphne is visiting KACL and has Frasier's headset up to her ear and then down on the console in a split second, with not enough time to do this naturally. (00:13:45)
Fool Me Once, Shame on You, Fool Me Twice... - S2-E14
Continuity mistake: Daphne visits the radio station where Frasier works about halfway through the episode. She holds the earphone piece up to her right ear, then it cuts to a different camera angle and the headphones are lying on the desk with no time between shots. It's actually quite glaring.
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.