When Frasier goes into his washroom to grab a towel, the towel is plain brown. In the next scene, the towel has stripes. And when he takes the towel into the kitchen, it switches between the two colors between shots.
The liberal candidate wants Frasier's endorsement because, "people love you". Except that the previous week, all of Seattle hated Frasier because he denigrated the city.
Traffic report helicopters rarely if even fly at night. There is dramatically less traffic in the hours between 9 pm and 6 am. So, they just are not necessary.
While Martin's political ad is being broadcast for the first time (the one where he was supposed to have mooned the camera), Frasier and Niles are setting up a chess game. But both sides on the chessboard have very dark pieces. Usually, the sides have noticeably different coloring (one lighter one, usually white or ivory and the other a dark brown, red, or black) but in this case, both sides were very dark.
Near the end, Frasier is sitting in the Eames lounge in his apartment. Behind him, a power cord is clearly visible coming right through the window, where there theoretically should be glass.
Frasier refers to "kidney pie" as a nadir in British cuisine. There is no such specialty. The nearest would be "steak and kidney pie".