The usual casting process for a sketch was that the lead role would be given to the member who came up with the idea. Sir Michael Palin has said that if he'd known the abuse he would have to tolerate as the "It's..." man, he never would have suggested the idea.
The Pythons did almost all of their own stunts, including Graham Chapman (a qualified mountaineer) reading a sketch while hanging upside-down on a rope, and Sir Michael Palin plummetting fifteen feet into a canal in "The Fish-Slapping Dance" after John Cleese smacked him in the head with a trout.
The phrase "And now for something completely different" was taken from a real phrase often used by the BBC during their television and radio broadcasts.
The Knight in shining armor who cropped up sporadically throughout the show was played by Terry Gilliam, the American member of Monty Python, who normally provided the animated sequences. He worked seven days a week on them, and usually two all-nighters.
One of the first things the Pythons decided was to get rid of the obligatory, though often disappointing, punchline of most comedy sketches. The "Restaurant Sketch" (or "Dirty Fork Sketch") poked fun at this.