PricewaterhouseCoopers partners Brian Cullinan and Martha Ruiz managed Oscar ballots for years. A single wrong handoff triggered the La La Land Moonlight best picture mistake on live television.

Each category gets two envelopes — one for each stage wing. Cullinan gave Beatty the duplicate Best Actress card, not Best Picture, causing the La La Land Moonlight best picture mistake.

PwC accepted full responsibility within minutes of the broadcast. The La La Land Moonlight best picture mistake forced immediate accountability from an 83-year Oscar tabulation partner.

Beatty and Dunaway returned to present Best Picture in 2018 — a wink at the La La Land Moonlight best picture mistake before reading The Shape of Water as winner without error.

Moonlight became a milestone Best Picture winner; La La Land took six other Oscars that night. The La La Land Moonlight best picture mistake bonded both films in trivia forever.