"The oceans will fall into the sky and the trees will hang with fishes."
Moon says this of Higgs, that if the two men were to appear together in one place, the world would cease making sense. The dialogue is consistent in tone with the overblown style Moon and Birdboot speak in as critics. They use flowery language to maintain their puffed up egos as critics, even though this line in particular indicates the deep insecurity Moon feels about his position and identity. The phrase is also a bit muddled in its logic - oceans cannot fall upwards. A tool of Absurdist plays, mangled prose occurs often in The Real Inspector Hound.
"The skeleton in the cupboard is coming home to roost."
Birdboot and Moon identify Simon as the catalyst for the mystery to unravel at Muldoon Manor. Birdboot's line here is another example of the mixed metaphors used by Stoppard to illustrate the shortcomings of communicating through language. (Here, the phrase "skeleton in the cupboard", meaning a dirty secret, is melded with "chickens coming home to roost", an idiom about facing impending consequences.) Before this line, Moon misunderstands Birdboot, thinking his accusations of jealousy and revenge pertain not to the murder mystery, but his feelings for Higgs. Mangled language is used for comic effect and also as a tool of Absurdism.
"She's beautiful - a vision of eternal grace, a poem...
Birdboot waxes poetic about the actress playing Cynthia, struck by her beauty. He compares her to something heavenly, and refers to her as a living embodiment of art. Of course, his motives are less than pure. Though he praises her acting, Birdboot repeatedly uses his position as critic to seduce actresses, promising he can advance their career for returning his affections. This exalted language is undercut by Moon, cutting to the chase, later in the scene: "Trim-buttocked, that's the word for her." Moon knows what Birdboot is really trying to express.
"I think I'll go and oil my gun."
Magnus' euphemism for going to the bathroom has a loaded connotation in the context of a murder mystery. This is another example of Stoppard's sharp ear for lines that can convey several different meanings at one time - this line is slang, a metaphor, and a sly criticism of the heavy-handed exposition used in the murder mystery genre.
"...she's all cocoa and blue nylon fur slippers..."
In trying to seduce Cynthia onstage, Birdboot disparages Myrtle as a common housewife. She may be warm, homey and comfortable, like cocoa and slippers, but she cannot compare to the goddess in front of him. Birdboot conflates his attraction with loftier goals of advancing art, and this line exposes his distaste for those outside of the theatre world - even his own wife.
