The 7-hour documentary O.J.: Made in America is the longest film ever to receive an Oscar nomination.
Meryl Streep received her 20th acting nomination, breaking her own record.
This marked the first time since 1976 that a Best Supporting Actor winner at the Golden Globes failed to receive an Oscar nomination in the corresponding category. Aaron Taylor-Johnson won the Golden Globe for Best Supporting Actor, but was not nominated at the Oscars. Instead, his Nocturnal Animals (2016) co-star, Michael Shannon, was nominated in the category for his performance in the film.
When the time came to present Best Picture (the last award of the ceremony), presenters Warren Beatty and Faye Dunaway were mistakenly handed the wrong envelope backstage. Beatty held a duplicate envelope for the category Best Actress in a Leading Role (which was announced just minutes before and was won by Emma Stone for La La Land) in his hands while presenting the nominees for Best Picture. When Beatty opened the envelope, apparently becoming aware of the mistake, he hesitated to announce a winner. He then handed the card to Dunaway who announced the heavily favored La La Land as the winner for Best Picture. The three nominated producers Jordan Horowitz, Marc Platt and Fred Berger as well as the whole cast and crew of the film went up on stage. Horowitz gave his thanks first, up next was Platt during whose speech the mistake became known when the ceremony's producers ran through the crowd on stage looking for the faulty as well as correct envelopes. It became clear that Horowitz was handed the wrong envelope by Beatty, which stated "Emma Stone, La La Land, Best Actress in a Leading Role", upon accepting the award, while the right envelope announcing Moonlight as the real Best Picture winner had to be brought on-stage from backstage and was finally handed to Beatty. The crowd on stage became slowly aware of the mistake and, despite being already aware of the not winning, Berger still gave a speech thanking his family and ending his speech by stating "We lost by the way, but, you know." Horowitz, also being told about the mistake, stepped up to the microphone again and finally revealed to the public that Moonlight actually had won, showing the correct Best Picture card to the audience as well as the camera. Beatty additionally cleared up that he was handed the wrong envelope and also announced Moonlight as winner of Best Picture. After this announcement, the cast and crew of La La Land slowly left the stage, while the three producers handed their awards over to the team from Moonlight, which was able to finally give their speeches. While there already was an mix-up of winners at the Oscars in 1964, when Sammy Davis Jr. announced the winners for the two categories Scoring of Music (adaptation or treatment) and Music Score (substantially original) and was handed the envelopes for the two categories interchanged (eventually announcing John Addison as the winner for Best Scoring of Music when he wasn't even nominated in that category (André Previn was the actual winner, while Addison was the winner in the Music Score category)), Beatty and Dunaway's snafu remains the only time in Oscar history that a person or film was announced as a winner, when they actually weren't.
The late writer August Wilson received a posthumous Oscar nomination in 2017. He passed away in 2005.
La La Land erroneously being declared Best Picture is actually the second time a presenter had announced the wrong winner during an Academy Awards ceremony. During The 36th Annual Academy Awards, Sammy Davis Jr. was presenting the award for Best Adaptation or Treatment Score, but was mistakenly given the envelope for Best Original Score and announced Tom Jones as the winner. Given that the two categories had a completely different set of nominees and Tom Jones was not nominated, the error was recognized immediately and the correct envelope was quickly given to Davis, who announced Irma la Douce was the actual winner.
During the "In Memoriam" montage, Australian production designer Janet Patterson was mistakenly identified using an image of living Australian producer Jan Chapman.
Re-recording sound mixer Kevin O'Connell received his 21st Oscar nomination in 2017. He finally won in 2017, breaking his streak on being known as "Oscars' biggest non-winner". He lost on all his previous 20 nomination.
Moonlight became the first LGBT themed movie to win Best Picture Oscar.
The day before the ceremony took place, the Academy decided to rescind Greg P. Russell's co-Oscar nomination for Sound Mixing (for the film 13 Hours). The decision was made because Russell violated Academy campaign regulations, since he contacted voting members to make them aware of his work on the film and his nomination. However, campaign regulation prohibit telephone lobbying. Russell shared his nomination with Gary Summers, Jeffrey J. Haboush and Mac Ruth, who all remained eligible for the award.
Best Supporting Actress winner Viola Davis became one of only nine actors to have won both the Tony and the Oscar for the same role on stage and film. The others are Yul Brynner (The King and I), Rex Harrison (My Fair Lady), Anne Bancroft (The Miracle Worker), Joel Grey (Cabaret), Paul Scofield (A Man for All Seasons), Shirley Booth (Come Back, Little Sheba), Jack Albertson (The Subject Was Roses) and José Ferrer (Cyrano de Bergerac).
First time since The 70th Annual Academy Awards that all four winners in the acting categories won for playing fictional characters.