Revealing mistake: It's clear the "Manchester" pub scene was filmed in the United States, as the pint glasses used are American pints and not imperial pints as used in the UK, which are approximately 20% bigger.
The First Temptation of Daphne - S9-E3
Revealing mistake: Frasier and Martin are arguing in the kitchen about the cricket. Martin opens the fridge to grab a beer and slightly bumps the fixed island in the kitchen, which moves.
Revealing mistake: After Donny puts the phone onto speaker you can see him deliberately wiping the mustard from the sandwich across his left cheek to prepare for the gag at the end of the scene. (00:06:45)
Match Game - S11-E18
Revealing mistake: 4 minutes into the show, Frasier gets off the elevator and goes to an office door with keys to open it, he tries the keys and they don't work. He realizes he missed his floor. A woman opens the door and they start talking about a dating service which he says he doesn't need, and he pushes the elevator down button, which lights up. The doors open and a man gets off. It's going up, which he finds out from an ex-girlfriend on the elevator. The down button light goes out before he gets on to go up with her. The light should only have gone off on the way back down.
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.