Mythology Gag/Theater

"What's in the punch. Lemons and melons and pears. Oh my."
 * In Rent, the guitar riff Roger plays is Musetta's Waltz from Puccini's opera La Boheme, as mentioned in the show. Another snippet from the opera turns up as an interlude in the title song.
 * The first few lines of Musetta's Waltz are copied almost word for word in "Take Me or Leave Me".
 * Not to mention that the line "They call me Mimi" was taken directly from the opera.
 * Older Than Steam: Characters in Shakespeare's Twelfth Night refer to Lucrese and to Troilus and Cressida's love.
 * While in Hamlet, Polonius notes that he once played Julius Caesar.
 * Tanz der Vampire, adapted from The Fearless Vampire Killers, makes the 'ah-ah-ah' melody Sarah and Herbert sang in the bath in the film into a major Leitmotif.
 * Alice in Wonderland Jr. uses the first line of music from "It's A Small World" when Alice shrinks.
 * The introduction to the Caucus Race has a few measures of "Under the Sea".
 * Wicked has a metric ton of these, mostly based on the the original Wizard of Oz film. Best example is probably


 * The 1995 concert version of Anyone Can Whistle had Angela Lansbury as narrator stating that she was the mayoress of a town much like the one in the musical some 31 years ago "for a very short term." The original production opened in 1964, and ran on Broadway for only one week.