Most television shows will go for the low-hanging Shakespearean fruit.
Not, at least in this case, Elementary.
It's brief, but we have a nice quote from Antony and Cleopatra in the middle of a Season Five episode:
The line is Cleopatra's. After beating up a messenger who brings her news that Antony, returned to Rome, has also returned to Octavia, she asks him to come back, promising not to hurt him any more. To encourage him to elaborate on his news—or just to confirm it—she says, "Give to a gracious message / An host of tongues, but let ill tidings tell / Themselves when they be felt" (II.v.86-88).
Naturally, Sherlock recognizes the quote immediately (I, for one, had to look it up). But he's slower on the uptake about its purpose (that I got pretty quickly).
It's brief, but it's interesting—the more so since it's not a usual go-to quote from or allusion to Shakespeare.
Links: The Episode at IMDB.