The live version of "Supper's Ready" on the box set has Peter break into his usual pre-song story, which is supposed to be punctuated by Phil's drumming at two points. Phil apparently missed the cue, and the result is hilarious.
Peter: "Phil, there's people out there!"
Phil: "I'm really sorry, everyone. I wasn't paying attention to what he was saying."
The second time around, Phil gets a massive round of applause when he actually comes in on cue.
Speaking of "Supper's Ready", there's the "Willow Farm" section, both in regards to both the music itself and for Peter prancing about as a flower.
"There's Winston Churchill dressed in drag, he used to be a British flag, plastic bag, WHAT A DRAG!"
"THE FROG WAS A PRINCE! THE PRINCE WAS A BRICK, THE BRICK WAS AN EGG, THE EGG WAS A BIRD!"
One bootleg features an audience member shouting something that can't quite be made out. Gabriel's very calm, deadpan reply was, "My mother does not suck cocks.".
"Jesus He Knows Me" mixes an absolutely hilariousvideo with a vicious lampooning of televangelism.
The video for "I Can't Dance" had many of these, and the video for "Anything She Does" features Benny Hill doing his usual shtick.
"You have arrived at your destination." [It's an empty field.]
"Have you been drinkin', luv?"
The Three Sides Live concert video for Who Dunnit?. Highlights include:
Phil Collins trying to pull his shirt over his head.
Mike Rutherford fooling around on Phil's drum kit, and awkwardly watching Chester Thompson to keep the tempo in check. He's clearly out of his depth playing Collin's (left-handed) kit, and he mostly just slaps the snare drum and one of the toms.
Tony Banks, who hated the song more or less from the beginning, staring glumly at his keyboards, wishing he would rather be anywhere else.