*The following contains minor spoilers for Bill and Ted Face the Music. *
Bill and Ted Face the Music tells a story decades in the making, where our two titular heroes finally work to create the iconic song which will bring the world together, as foretold by the future. That meant that everything in the film was building to the big musical moment, and it truly needed to be something special. Of course, actually trying to create the greatest song ever would have been a herculean task, and director Dean Parisot admits that in the end, they didn't really try to do that, but the movie did start in the perfect place for a movie trying to do something special with music, The Beatles.
Music is often one of the last things to be added to a film, which means that, even as the final sequence of Bill and Ted Face the Music was being filmed, the actual song being performed hadn't been written yet. But since the movie needed some music to play in the scene so that all the performers looked to be playing together, Dean Parisot tells Polygon that they used a Bclassiceatles tune. Parisot explains...
From the beginning, for seven years, I kept saying, ‘We gotta get this song!’ But as it as it evolved — for me, what’s wonderful about the movie is the last sentence, ‘It wasn’t so much the song as the fact that everyone played it together.’ That really is the heart of the movie, thematically. So we didn’t have to make the best song ever written, that would be a dubious thing for anyone to try to attempt, especially an independent movie like this. But I think we were very successful at creating that song, eventually. We had a really great music supervisor, Jonathan Leahy, and we sort of Frankensteined it together. We didn’t have it yet when I was shooting that sequence. We shot that whole sequence to ‘Ob-La-Di, Ob-La-Da.’
While maybe not the Beatles single most popular track "Ob-La-Di, Ob-La-Da" is a great song and in its own way, it works as a song that's meant to bring the world together, as it's about simple things, that most people from any place or time would likely be able to relate to. If you've somehow never heard it, give it a listen below.
So when you see Wyld Stallyns playing together at the end of Bill and Ted Face the Music, they're all actually playing along to this. Of course, that meant that when it came time to actually write the song, called "Face the Music" in the film, they had to keep the same tempo so that everybody still looked like they were playing the new song. As it happened, that all worked out. Dean Parisot continues...
Yeah, we used it as a reference track in playback as we were shooting. In the film, everybody’s attempting to play to that song. And then when we created the song, we kept the same tempo, and it worked perfectly. Go figure.