These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Monty Python and the Holy Grail
Acceptable Targets: The French, naturally. It's a British film. Why else would they have that outrageous accent? Also, the BLOODY PEASANTS.
The opening credits' moose dialogue at the bottom.
The Sun and clouds jumping up and down, causing an earthquake.
Brick Joke: Meta. In Life of Brian, Brian uses his (Chapman's) prominent Roman nose as proof that he is part Roman. Arthur, also portrayed by Chapman, is historically said to have been Romano-British.
Incidentally, Chapman also played Raymond Luxury Yacht in the series, who appears on set with a huge fake nose.
Crosses the Line Twice: The Black Knight getting dismembered. John Cleese admitted as much in his commentary track. He explained that some viewers in America found the sequence horrifying because of Vietnam War footage on the news; however, he noted that they began to laugh when BK's first leg got hacked off and he was still raring to go.
Also Lancelot's "rescue" in which he charges into the castle and slaughters half of the townspeople under the belief that they're kidnappers. The heroic music and the fact that he turns his wrath on not only guards and peasants but the bridesmaids, the wedding band, and a torch on the wall make something that by all rights be horrifying absolutely hilarious.
Discredited Meme: The constant use of quotations from it has caused it to become popular to mock people for quoting it so much.
Ear Worm: The drawbar organ music during the "intermission" and at the end.
Ensemble Darkhorse: The Black Knight, despite only being in one scene is arguably the most famous character in the film.
Fountain of Memes: One of the single most quoted works within "nerdy" circles. More or less every single line is a meme to some extent. Find them here.
Stop Helping Me!: Galahad's reaction to Lancelot dragging him out of Castle Anthrax.
The Weird Al Effect: It can be very hard to take Arthurian legend seriously after seeing this movie. There have also been reports of audiences bursting into laughter during violent sequences in movies like Excalibur.