Daphne brings over a tray of snacks (carrots, celery, cheese) at the beginning of the "Nightmare Inn" rehearsals in Frasier's apartment. Outside of Roz eating some cheese, the snacks remain untouched. But when Mel White decides to quit the production, almost all the snacks seem to have been eaten.
Gil Chesterton's character refers to his boyhood in Surrey where he "played in the fens". There are no fens in Surrey.
Niles asks Roz for the name of her character. Only a minute earlier, he addressed her character as his mother.
In many episodes some of the actors, both stars and extras, can be seen breaking character in the background, usually laughing, at the main action. In this episode Peri can be seen laughing at David killing off his character at the microphone. She won't be able to help herself later in "Voyage of the Damned" (Season 5) when Frasier gets champagne thrown in his face at the bar.