The Act 1 Scene 2 title card, "What, Me Worry?," is the famous slogan of Mad magazine's fictional mascot, Alfred E. Neuman.
Niles and Frasier are driving north on 5th Ave N in the opening scene. They start at the intersection of 5th and Denny and end at about 5th and John. This is a further display of the accuracy taken by the show: 5th Ave N is located just on the opposite side of the Seattle Center from Frasier's apartment, and it would be one of two roads he would take.
Dr. Karnofsky's office is located on Queen Anne Hill, directly up from Frasier's apartment location in Lower Queen Anne. This can be discerned by the view out of the office window.
The cut on the bridge of Frasier's nose from the minor accident, is real. The weekend the episode was filmed, Kelsey Grammer hurt his nose in a car accident. Grammer also got two black eyes from the accident as well. He also broke his ankle in the accident as well. He said in an interview: "I was driving around by the set, and the person in another vehicle slammed into me, and my nose went into the wheel. When I woke up from the daze I was in, I looked in the mirror, there was a large gash across the bridge of my nose, and I went to the hospital for an x-ray. And it turns out I also broke my ankle. And got two black eyes. I was also in a lot of pain."
Regan's apartment number is 1923.