Lady Gaga, Julie Andrews notch Oscars' top social media moment

Lady Gaga performs songs from "The Sound of Music" during the 87th Academy Awards in Hollywood, California February 22, 2015. [Photo/Agencies]

About 13 million people viewed 5.9 million tweets in the United States about the Oscars on Sunday night.

Show highlights included host Neil Patrick Harris wearing just his underpants on stage in an homage to a scene from "Birdman," the audience receiving Lego Oscar statues during the "Everything Is Awesome" performance from "The Lego Movie" and John Travolta's apology to Idina Menzel for flubbing her name at last year's ceremony.

On Instagram, it was Oscars presenter Ansel Elgort's photo with his mother as his date to the ceremony that earned the most "likes" - more than 733,000.

The Oscars, aired live on Walt Disney Co's ABC, saw a sharp dip in viewership, with 36.6 million people in the United States tuning in to see frontrunners "Birdman" and "Boyhood" battle it out for the night's best picture prize. "Birdman" won, while "Boyhood" was shut out of the major categories.