Despite such gaffes, however, the stars carried on, following the age-old adage that the show must go on.
Here were the night's biggest missteps:
Adele restarts George Michael tribute
The British diva opened the show with a flawless performance of her Grammy-winning song "Hello," and she returned to perform George Michael's 1996 song "Fastlove" in tribute to the pop star, who died Christmas Day. Not long into the song, in which her pitch sounded off, she stopped and asked the show's producer if she could restart.
"I know it's live TV," she said, followed by an expletive that was bleeped out. "I can't do it again like last year. I'm sorry for swearing, and I'm sorry for starting again. Can we please start it again? I'm sorry, I can't mess this up for him."
By the end of the performance, she had audience members on their feet and many of them in tears. She wiped away tears at the end, later telling reporters backstage that she was "devastated" that the performance didn't go the way it did in rehearsals and that she had been planning a tribute to Michael since the day after he died.
Adele, 28, suffered an audio glitch last year during her Grammy performance of "All I Ask," throwing off her performance. She later explained that a microphone had fallen onto the piano strings.
Metallica singer's microphone doesn't work
After several verses, Hetfield moved over to Gaga's mic, which was working, until his mic could be fixed. The rest of the performance went off without a hitch and ended with crowd-surfing by Gaga. But Hetfield was obviously not pleased, as he kicked down his mic stand when it was over.
Laverne Cox forgets to mention Metallica
Realizing her gaffe, Cox later tweeted and apology:
Adele's 'Hello' co-writer cut off
After co-writers Adele and Greg Kurstin won song of the year for "Hello," she first apologized for swearing during her tribute to Michael. "George Michael, I love him. It means a lot to me. I'm sorry if I really offended anyone anywhere," she said, before going on to thank members of her team and Kurstin.
The move drew boos from the audience. Fortunately, Adele made up for the show's gaffe by letting Kurstin have the mic first when they won the next award, record of the year, also for "Hello."