” ― “Sir Beldevere: What makes you think she's a witch? GUARD: Well, I'll ask him, but I don't think he'll be very keen.
At some point, the plan was to have half the movie happen in the Middle-Ages and the other half in modern times.
John Cleese estimates that no more than 15% of the original script remained by the time filming started.
Originally an inspector was going to be following them around and attempting to find them, and does, at the end.
Source: Monty Python and The Holy Grail (Book) A First Draft by all of the Python members.
The ending actually was modified; it was supposed to be Arthur and the army sieging the French castle when they were saved by a bunch of sparrows dropping coconuts (in reference to the argument Arthur had at the beginning with the man in the castle as to whether or not a swallow was capable of carrying a coconut).
They ran out of time and money so they put in the police arrest scene instead.The original draft actually has a much different ending.It's been transcribed here: is not to contradict others who said the ending was what was in the original shooting script. ARTHUR: It is King Arthur, and these are my Knights of the Round Table. GUARD: This is the castle of my master, Guy de Loimbard! GUARD: Oh, yes, it's very nice-a (I told him we already got one) ARTHUR: Well, um, can we come up and have a look? Why do think I have this outrageous accent, you silly king! I blow my nose at you, so-called Arthur-king, you and all your silly English knnnniggets. If he will give us food and shelter for the night he can join us in our quest for the Holy Grail. ARTHUR: Go and tell your master that we have been charged by God with a sacred quest. Using the police to end the picture was a cheaper and much easier solution.I have no idea why, but I have a copy of the first draft of the Holy Grail. They didn't change that, but they took out the parts that lead up to it in the script.And five minutes before the take it's fairly radically rewritten. I didn't hear any mention that the cost was a motivation for cutting parts of the script.So in fact at the very last minute there's usually these little extra bits creep in. Whether it was or not, the ending was clearly planned well before filming began, for artistic reasons to boot, so it's not a case of running out of money.