Eliza's trip to the horse races, where she demonstrates that Higgins may have taught her the posture and pronunciation of a lady, but he overlooked details like sentence structure, word choice, and subject matter, carelessly instructing her to stick to "the weather and everybody's health."
Eliza's Imagine Spot in which the king of England grants her request for "'Enry 'Iggins' 'ead," and has his guards shoot Henry Higgins at her call. Then the real Higgins enters at the top of the staircase, causing Eliza to glance awkwardly at him, then at the carpet which she imagined his corpse falling on top of.
"Damn damn damn damn! I've grown accustomed to her face!" Doubles as Heartwarming.
Mrs Higgins response to having the archbishop and the professor together: "Good heavens, no! I shall be excommunicated!"
Higgins' quip that Americans haven't spoken English in years. It's one thing to say that the play was set in 1912, remember that the original Pygmalion version was written at that time as well. If Americans weren't speaking proper English a hundred years ago, what would Higgins say to our speech today?
Pickering talking in Eliza's accent then mistakingly thinking Higgins was talking to him when he said "Try it again."
Pickering: Those strawberry tarts are delicious. 'Ave you troid the ploin cayke?
Higgins:[looks at him, speaks to Eliza] Try it again.
Pickering: Did you try the...
Eliza and Mrs. Higgins having tea and casually discussing Higgins' rude behavior, with Higgins sulking like a ten-year-old behind them.
Mrs. Higgins: Henry, don't grind your teeth.
Higgins' blatant attempt to secure Eliza's cooperation with chocolate (physically putting a piece in her mouth himself, no less)... actually works.
Eliza: I wouldn't 'ave et it, only I'm too ladylike to spit it out.