Continuity mistake: Frasier puts the tuna on the coffee table for Mr. Bottomsley and the cat jumps up and starts to eat it - he is facing the couch. In the next shot we see Eddie come into the room and suddenly the cat has moved and is facing Marty's chair - without enough time for the change.
Continuity mistake: Frederick is visiting and sitting on Frasier's couch with headphones on, playing a Gameboy. Frasier pulls off Freddy's headphones, which then lie around his neck while Frederick continues to hold the Gameboy. In the next shot, the headphones and Gameboy are on the coffee table and Freddy is sitting quite a bit to the left of them.
Continuity mistake: Frasier, Regan, Niles, and Poppy are at the ball - Frasier asks Regan to dance and she leaves her purse on the table, where we can see the strap hanging down over the edge. A couple of shots later, as they dance by, we can see the purse has changed position and the strap is lying on the table.
Factual error: This episode takes place on Frasier's birthday - Martin had ordered a copy of the newspaper published the day Frasier was born and it is sitting on the dining room table when Daphne glances at it and says "Queen Elizabeth's had another baby." - in the Episode The Late Dr. Crane earlier in the same season, Frasier was mistakenly reported as dead on a local TV news show. The dates for his life were shown on the show as 1952-1999. The Queen, in fact, did not have a baby in 1952.
Continuity mistake: In the opening scene, Ronee and Frasier are talking at his table about her mother. Frasier asks, "She doesn't approve of premarital sex?" and his arm is folded in front of him. In the next shot, his elbow is on the table and his hand up in the air. Later on in the scene, Ronee's mother shows up at the door and we see Marty lunge to the right to grab his cane. A couple of seconds later the shot goes back to him and we see him lunge to the right for his cane again.