The two ended up driving in Paul's hometown, Liverpool, instead of in Los Angeles, and made stops at significant places in the Beatles bassist's life - from the now-famous Penny Lane, to his childhood home, to one of the pubs where The Beatles used to play before they became big stars.
The pair started the show singing the Beatles hit Drive My Car, while cruising through the city, replacing the song's "beep beeps" with honks of the horn. "Can you please, please help me" before joining Paul in a rendition of Drive My Car.
Even Corden himself agreed that it was his favourite edition of the show to date. "Couldn't you sing she loves you yes, yes, yes?' And we were like, no", said McCartney. They also stopped by the barber shop mentioned in "Penny Lane" and mingled with excited fans along the sidewalks. Oh, and a little song called "Let It Be".
As they look around, Sir Paul says one of the downstairs rooms is where "me and John would often come to rehearse or to write".
The video also saw the legend revisit his childhood home on 20 Fortlin Road, where he told the incredible story of how he and John Lennon wrote She Loves You and played it for his father.More news: Sweden edge South Korea
Corden said it was the "most lovely story" he had ever heard, before singing a teary rendition of the song.
The Late Late Show host then began to cry and revealed that his grandfather and father once sat him down and played him Let It Be.
"I got a fucking text from him [the next day]", he said. "Couldn't you sing She loves you, yes, yes, yes?'" "I remember me and my mom and dad".
'I think if my grandad was here now he'd get an absolute kick out of this'.