In Monty Python and the Holy Grail, rules and order might be one of the last things you'd expect. Arthur travels through a kingdom where any sort of normal protocol is out the window. He's berated by a peasant. Cute bunnies are killer monsters. Knights are chickens. Horses are coconuts.
When we look at some scenes on a smaller scale we see rules and order everywhere… but they're only there to be subverted. We see a "dead collector" who's a stickler about regulations and a bridgekeeper who lets no one cross without a rigorous and formal interrogation. Order exists only to be upended—even the idea of filmmaking as an orderly and sensible endeavor is deliberately lampooned by these masters of disorder.
Having specific rules in absurd situations throughout the film adds to the irony: the audience is experiencing a story that itself seems totally bereft of order.
It's only through representing a sense of order that a parody can function. The film is orderly in its narrative structure with the purpose of subverting that order within specific contexts of the story.
The Middle Ages were a time of transition when it comes to religious beliefs and traditions. On the one hand, they signaled the rapid spread of Christianity; on the other they were affected by lingering pagan beliefs—there are a lot of non-Christian legends like the Lady of the Lake and Excalibur, as well as sorcerers and monsters.
Of course, Monty Python and the Holy Grail doesn't just ridicule the pagan side of things. The Holy Hand Grenade of Antioch is some biting commentary on the intersection of religion and violence. The flagellant monks and even God himself get skewered. The Pythons were always irreverent, but The Holy Grail was their most serious and focused effort to lampoon religion… until Life of Brian blew it out of the water.
The entire film blows up the beloved British tradition of knights in shining armor, not to mention chivalry, chastity, courtly love, and courage.
The entire film blows up the traditional process of filmmaking.
There are all kinds of crazy, and usually ironic, power dynamics found throughout Monty Python and the Holy Grail. Arthur and his knights, despite being the brave and famous company of heroes from ancient lore, are essentially helpless. Arthur is dissed by a random guard with an interest in swallows, a politically minded peasant, a castle of rude Frenchmen, and knights who like to say a particularly nasty word too shocking to reproduce here. (Not really; they say "ni.")
Then there's the power of violence: Arthur maims the Black Knight and Lancelot carves his way through a wedding. Power is always important when you're dealing with a tale of adventure. The Holy Grail, however silly, is no different. And Dennis makes some pretty good points about power struggles among the social classes.
The Holy Grail subverts the normal quest narrative because, instead of gaining power and succeeding, the protagonists fail at everything.
Knowledge is the truest form of power in The Holy Grail. The Frenchman, the swallow-guard, Dennis, Tim, the Knights Who Say Ni: each of them is powerful because they possess some specific knowledge. The swords and shields of the Knights of the Round Table are useless.
Monty Python, being primarily a TV and film comedy group, is always about the visual. Sometimes just the absurd appearances of the characters are enough to send us rolling in the aisles. And these appearances are paired sometimes with very fitting behavior, like the inane and more-than-a-little-daft guards, or the silly armor of the Frenchman.
But other times we get something totally incongruent: a fluffy white bunny that's a maniacal killer? And wicked enchanter who's named Tim? A filthy mud-digging peasant who could write a treatise on the repression of the lower socio-economic class? The audience is always both taught when to laugh and tricked into laughter by visual appearances in Monty Python and the Holy Grail.
The deceptive appearances in The Holy Grail contribute to the films subversions of typical fantasy stereotypes. It's not all about getting a few laughs; it's about how people expect things to appear versus what they actually are.
The Holy Grail is a film about the need to maintain certain appearances in order to survive.