To Thine Old Self Be True - S7-E20
Corrected entry: In earlier episodes Niles has talked about how Maris' food issues go back to her childhood, for example that she had to be taken to hospital to be force-fed as a child. But in this episodes, he claims that she was always chubby as a child.
Something Borrowed, Someone Blue (2) - S7-E24
Corrected entry: In the scene where Roz and Daphne are discussing seating arrangements, Roz makes a comment about Frasier and Niles going to prom together, to which Frasier elaborates defensively that they did not attend the prom "together" but that their "dates were sick and they went stag." Frasier and Niles would most certainly not have gone to the prom together, considering they are six years apart.
Dark Side of the Moon - S7-E22
Corrected entry: Frasier lives in a high rise, apparently on the 19th floor (his is 1901). When Daphne throws the other tenant's laundry off the balcony, we hear the crash of cars below within a second or two (she had earlier explained to her therapist that she caused a car accident). In real life, of course, it would have taken longer for them to reach the ground.
Correction: "Childhood" can be any year before a person becomes a legal adult. It's quite possible that Maris was chubby before age twelve or so, then she developed the issues in her teens and had to be force-fed. Indeed, eating disorders and food issues often start in the teenage years.