Bilingual Bonus - There are some lines that are in German, French, and Italian, and some Sanskrit words.
The Latin epigraph translates to: Once with my own eye I saw the Sybil of Cumae, hanging in a jar, and the boys were saying to her: "What is it you desire?" She responded, "I wish to die."
Oh, and the dialogue there is in Greek.
Bread, Eggs, Milk, Squick - The narrator in the first "Unreal City" section talking to Stetson. "That corpse you planted last year in your garden..."
Perhaps not as squicky as it first appears; "That Corpse" might refer to the Corpse Flower, whose fragrance resembles rotting meat.
Though, considering that he just mentioned the battle of Mylae...
The narrator of the first section of A Game Of Chess suggests this agenda: "The hot water at ten. / And if it rains, a closed car at four. / And we shall play a game of chess, / pressing lidless eyes and waiting for a knock upon the door."
She had become notorious a couple of decades earlier as the go-between for Austro-Hungarian Crown Prince Rudolf and Baroness Marie Vetsera. After the Mayerling incident, she was essentially frozen out of Vienna society and went into self-imposed exile. She met Eliot in 1911 (or 1914 according to some sources) and the lines in Burial of the Dead are said to be taken nearly verbatim from her remarks during their conversation.
Ironic Echo - Some of the allusions, like all that nightingale business. Also some internal examples, like "death by water" and the "pearls that were his eyes".
The Burial of the Dead's "know[ing] nothing" is echoed in A Game of Chess.
Lampshade Hanging - "The fragments I have shored against my ruins," at the end of the poem; referring to fragmented sentences he put before this line. Also, the second part of The Burial of the Dead mentions "a heap of broken images"— like the poem itself.
Though it can be argued that the cynicism is moderated, to an extent, by the ending stanzas of the last canto, What The Thunder Said, in which Eliot proposes three virtues (using one of the most famous sections of the Upanishads) - charity, mercy and self-control - as means of escaping the sterile Waste Land of modern civilization.