Continuity mistake: Frasier is in the hospital waiting room and Phil (the guy who later pretends he is Frasier) is reading a newspaper - he folds it up before talking to Frasier but in the next shot, from another angle, we see him folding it up again.
Continuity mistake: Niles has just met Mel in her office, and she is wearing a white coat - she is brushing off her sleeve in one shot, and then unbuttoning the coat in the next, without enough time to have switched that quickly.
Answer: Nanny G (Nanette Guzman - played by Laurie Metcaf) has been a children's entertainer for twenty years, and tells Frasier, "Do you know what it's like to play the same character for 20 years?!" The joke is that Kelsey Grammer has been playing Frasier Crane since 1984, when the character first appeared on "Cheers", so Kelsey in real life has been doing just that!
Super Grover ★