The violence inherent in the system

Monty Python and the Holy Grail

(1975)

As I watched the first scene, I remembered reading somewhere that in medieval times it was thought that some birds wintered under the mud--that widespread awareness of bird migration didn't come about until centuries after AD 932. So naturally I checked Wikipedia immediately after the film ended:

Aristotle . . . suggested that swallows and other birds hibernated. This belief persisted as late as 1878, when Elliott Coues listed the titles of no less [fewer] than 182 papers dealing with the hibernation of swallows. It was not until early in the nineteenth century that migration as an explanation for the winter disappearance of birds from northern climes was accepted.

I'm sorry, but that changes--spoils--everything. How can we take anything in this film seriously when the opening scene so violates verisimilitude?