Album Title Drop: "She sprinkles flowers in the dirt, that's when a thrill becomes a hurt", from the song "That Day Is Done".
There's a partial one in the song "Fine Line": "There is a long way between chaos and creation" (the album in question being Chaos and Creation in the Backyard).
Alternate Reality Episode: Three albums released under the name "The Fireman", a "group" consisting of Paul and the record producer Youth. The first two albums were sound collages. Electric Arguments, still rough and unpolished but a more conventional collection of songs, got strong reviews.
There was also his and Linda's 1971 (but not released until 1977 due to other obligations) Thrillington project (an orchestral album consisting of covers of Paul's entire Ram album), credited to the pseudonym Percy "Thrills" Thrillington.
Analogy Backfire: The analogy of piano keys representing racial harmony in "Ebony and Ivory" falls apart when you try playing a C and a C-sharp at the same time. Musical notes that sit side-by-side on the keyboard do not get along, regardless of colour.
They do if played as part of a chord. GMaj7, for example sounds fine with a black and a white key next to each other(doubling the root at the octave). Major 7th chords are actually quite common in The Beatles music. Not to mention that the song itself features a bunch of pedal tone chords that don't take away from the Major tonality of the song, some of which do in face feature black and white keys played next to each other, making the example a somewhat Genius Bonus for the musically trained.
Divorce Assets Conflict: Part of the extremely ugly end to his second marriage, with model Heather Mills. Mills got a large sum that was still less than a fifth of what she wanted, along with the judge's assessment that she was "less than candid".
Embarrassing First Name: His full name was James P. McCartney. You wouldn't think James was all that embarrassing but no fewer than three post-WW1 British prime ministers have had the same aversion: James Ramsay MacDonald, James Harold Wilson and James Gordon Brown. Another was more enthusiastic, or maybe saw it as the lesser of two evils: Leonard James Callaghan. Word of Biographer has it that everyone called him Paul to avoid confusion with his father, James 'Jim' McCartney.
"Non nobis solum "Sed toti mundo "Nati "Toti mundo nati"
Greatest Hits Album: He's had several. Wings Greatest covers mainly Wings, but has some early solo tracks. All the Best is under Paul's name, but is about half Wings. The two-disc Wingspan is the most comprehensive collection, covering both Wings and Paul's solo output through 1984.
Intentionally Awkward Title: Kisses on the Bottom. It's a line from "I'm Gonna Sit Right Down and Write Myself a Letter," and in that context clearly refers to signing love letters with X's, but still... Paul...
Long Runner Line Up: After two groups that didn't qualify (The Beatles only lasted eight years after Ringo joined, and aside from the core three of Paul, Linda and Denny Laine the Wings were a Revolving Door Band) his current live band - and at times going along in the studio - qualifies, having been the same musicians since 2001.
Missing Mom: Mary McCartney died from cancer when Paul was 14. This tragedy has undoubtedly inspired quite a few of his songs, including "Let It Be", and helped him bond with John Lennon, who'd also lost his mother at a young age.
New Sound Album: Plenty of his earlier solo stuff was Synth Pop-ish, compared to his later music, which had a harder rock sound to it. Later on, his 2013 solo album, which he specifically had produced by a younger staff, was given a mostly electronic rock style rather than straight-up rock (as with his previous albums), complete with electronically distorted guitar audio. Fittingly, the album is called New.
Older than They Look: He's 70, but he looks like he's in his late-40's to mid-50's. One reason for this is that his hair used to be greyer than it is now.
Parental Substitute: Julian Lennon has admitted that he was much closer to Paul than his own father, especially during his early childhood and adolescence. When John deserted Julian and his mother, Paul stepped in as a role model and even wrote the song "Hey, Jude'' to console a young Julian over his parents' divorce.
“Paul and I used to hang about quite a bit—more than Dad and I did. We had a great friendship going and there seems to be far more pictures of me and Paul playing together at that age than there are pictures of me and my dad.” - Julian Lennon
Prison: McCartney's infamous bust in 1980, when, as he and Wings were arriving in Japan on a tour, he was caught at customs with 218 grams of marijuana in his luggage. He spent ten days in jail and could have faced a seven-year sentence, but the Japanese government elected to deport him. Reports of John's reaction to the bust range from "delighted with his ex-partner's misfortune to the point where he literally danced with joy" to "furious that his friend let himself get caught and increasingly anxious as Paul was detained"; at any rate, he called to provide moral support.
Rerelease the Song: "Maybe I'm Amazed" and "Coming Up" were solo songs which also saw live releases by Wings. "Another Day / Oh Woman, Oh Why", his debut single, was also made available for Record Day 2012.
Rooftop Concert: Naturally, played with the other three Beatles in the band's final performance on the roof of Apple Corps, but Paul has also done it solo, having played on the marquee of the Ed Sullivan Theater on The Late Show with David Letterman.
Self-Titled Album: McCartney (his solo debut, in which he belatedly announced the breakup of the Beatles) and the later McCartney II.
Significant Anagram: While it's unclear whether it's intentional, Memory Almost Full can be rearranged to spell "For My Soulmate LLM".
Supergroup: Performed a new original song called "Cut Me Some Slack" with the surviving members of Nirvana for the "12 12 12" benefit concert. It rocked.
Take That: "Too Many People" off of Ram is a rather veiled Take That towards John Lennon. The photo on the inside sleeve of Ram—a beetle...er, screwing another beetle—is less veiled, though Paul intended it as a reference to the acrimonious collapse of the Beatles instead of specifically insulting John. Lennon, always more willing to get nasty than McCartney, took his revenge with "How Do You Sleep?".
Word of God is that only the line "too many people preaching practices" was about John and Yoko, and "you took your lucky break and broke it in two" was about John's part in the Beatles' dissolution. John thought the whole album was about them.
While the common misconception is this, McCartney's reason for being angry at Jackson seemed to change from MJ "buying the rug he was standing on," to some of the choices he made in exploitation of the songs (e.g. putting certain Beatles songs in certain commercials) to simply not giving McCartney—one of the wealthiest men in showbiz—a raise in the royalties.
Paul and Linda's relationship with Denny Laine of Wings didn't end well, either, although Paul and Denny seen to have reconciled.
And, of course, Paul's relationships with the other Beatles melted down rather spectacularly in the late 1960s. They all later managed to patch up their differences to some degree following that, but there was reportedly never the same closeness.
Wig, Dress, Accent: During Beatlemania he took to wearing disguises so that he could wander the streets without being mobbed (and occasionally play pranks on the other Beatles and Brian Epstein). In one amusing incident, he was recognised by a bartender who wasn't fooled when Paul asked for "a drop o' the hard stuff" in an Irish accent. See also Paul and Linda incognito at a George Harrison concert.
Word Salad Lyrics: Paul was fond of these; "Junior's Farm" and "Jet" are two prime examples.