Allegedly, after Blade Runner tested poorly with test audiences, director Ridley Scott added a happier ending. This is the ending used in the original theatrical version of the film.
The ending where Deckard and Rachael fly away.
The footage flight used, is actually unused footage originally filmed for Stanley Kubrick’s The Shining. Kubrick gave Scott the footage on the agreement that absolutely none of the footage he ended up using in The Shining made it into Blade Runner.