Audio problem: Dr. Nora's mother is pounding on the glass of Frasier's booth. She then wags her finger at Nora but the sound of her pounding continues, even though she's no longer doing it.
Continuity mistake: When Dr. Nora's mother comes into Nora's booth, she locks both doors so Frasier can't get in. However, Nora gets upset, quickly gets up and opens the door, without having to unlock it.
Continuity mistake: Near the end of the show, Dr. Nora's mother is chasing Nora through the corridors of KACL, behind the windows of Frasier and Roz's booth. We can see them go by, from window to window. The shot then cuts to Frasier, looking horrified, and we see Nora's mother run by a couple of windows again - even though this could not possibly have happened in real time.
Answer: In the last episode, they explained that Tossed Salad and Scrambled Eggs is a metaphor for the mixed-up people to whom Frasier dispenses his radio psychiatric advice.