Turns out it's a little bit of both. He starts playing the songs, at least the ones he can remember, and soon enough garners the attention of none other than Ed Sheeran, playing himself in an extended cameo that's not exactly good, but still comes off as surprisingly genuine. Next thing Jack knows, he's being flown out to Los Angeles and courted by a money-hungry manager (Kate McKinnon). (No, he never tries to trot out "Octopus's Garden" only to be met with a resounding: WTF.)
It begins to become obvious that Curtis and Boyle are less concerned with the whole mystery of why the Beatles disappeared from existence and more concerned with the budding romance between Jack and Ellie. She's been harboring a deep crush on him for years; he has refused to take notice, and ultimately realizes the error of his ways. It's all very sweet. Patel and James are adorable together, especially during a long drunken sequence in -- where else? -- Liverpool. Still, it throws the general weirdness of the movie into relief, especially given that the Beatles aren't the only thing that's vanished.
Yes, let that soak in: There are other massively popular pieces of culture that do not exist in the parallel universe of Yesterday. But aside from the fact that people don't know what [insert major phenomenon] is, nothing else about the world changes. While the rom-com that's unfolding is cute, the mind reels at the kind of alternative histories Yesterday presents and does absolutely nothing with.
So what is excised from the planet? The band Oasis, for one. Alas, Liam and Noel Gallagher never get together to make beautiful music and shout profanities at one another. Now, this one sort of tracks, given that the lack of Beatles would have radically altered the state of pop music. However, the musical landscape hasn't radically shifted. Coldplay still exists, as do Ed Sheeran, The Killers, and perhaps most randomly, the Fratellis. Yes, the Fratellis, that Scottish rockers who were big in 2006 and have one song that's so similar to a Beatles track someone pointed it out online. They survived. How?
You know what else got wiped? Coca-Cola and cigarettes! Jack asks for a Coke and finds out there's only Pepsi. Later, he remarks that he would like a cigarette, and he is met with a blank stare. Cigarettes have never been invented, and yet the course of human history seems mostly unchanged. Have fewer people died of lung cancer? Was there ever a tobacco trade? What became of the Marlboro Man? Did Mad Men ever make it to air? These are questions that need answering.