From Wikipedia:

The Beatles recorded 25 takes of “Hey Jude” at Abbey Road Studios in two nights, 29 and 30 July 1968. These were mostly rehearsals, however, as they planned to record the master track at Trident Studios to utilize their eight-track recording machine (Abbey Road was still limited to four-tracks). One take from 29 July is available on the Anthology 3 CD. The master rhythm track was recorded on 31 July at Trident. Four takes were recorded; take one was selected. The song was completed on 1 August with additional overdubs including a 36-piece orchestra for the song’s long coda, scored by George Martin. The orchestra consisted of ten violins, three violas, three cellos, two flutes, one contra bassoon, one bassoon, two clarinets, one contra bass clarinet, four trumpets, four trombones, two horns, percussion, and two string basses. While adding backing vocals, the Beatles asked the orchestra members if they would clap their hands and sing along to the refrain in the song’s coda. Most complied (for a double fee), but one declined, reportedly saying, “I’m not going to clap my hands and sing Paul McCartney’s bloody song!”

Ringo Starr almost missed his drum cue. He left for a toilet break—unnoticed by the other Beatles—and the band started recording. In 1994, McCartney said, “Ringo walked out to go to the toilet and I hadn’t noticed. The toilet was only a few yards from his drum booth, but he’d gone past my back and I still thought he was in his drum booth. I started what was the actual take, and ‘Hey Jude’ goes on for hours before the drums come in and while I was doing it I suddenly felt Ringo tiptoeing past my back rather quickly, trying to get to his drums. And just as he got to his drums, boom boom boom, his timing was absolutely impeccable.”

I like the bit about two minutes in when George Harrison is rambling on and on about something and he finally asks George Martin “You know what I mean?” but it’s obvious that even though Martin nods his head in the affirmative, that he was no idea what Harrison meant.

Imagine if there was this sort of documentation of all of their recording sessions, eh?
 

 
The famous “Hey Jude” live promo film directed by Michael Lindsay-Hogg as it aired on The Smothers Brothers Comedy Hour.