After Frasier suggests to Bulldog that he could use a police sketch artist instead of his camcorder to record his date that evening, Dan Butler (Bulldog) momentarily looks at the camera as he leaves the studio.
When Frasier invokes Freud to influence Niles, Niles responds, "Oh, all right! But that was dirty pool, using a Freud quotation...it's the Crane boys' kryptonite." But we learn in season 1, episode 23 (Frasier Crane's Day Off) that Niles doesn't subscribe to Freud. In that episode Niles says, "I should warn you that while Frasier is a Freudian, I am a Jungian. So there'll be no blaming Mother today."