[peterfirefly]

How do we know that the Mahabharata wasn't changed some time after Big Al's "gap years to find himself"?

This sort of thing happened a lot with the Old Testament (despite being written down). I would be shocked if it didn't also happen with Mahabharata, which is famous for not having been written down (much).

[sanjit]

There were (loosely) almost checksums for the oral transmission of the Sanskrit versions of the Mahabharata for ensuring consistency and accuracy.

Priests were highly trained in recitation and memorization and the oral texts were consistent across vast regions.

My source is vague memory but I think it was from JAB van Buitenen speaking about oral transmission and accuracy in the intros for either “The Bhagavadgita in the Mahabharata” or “The Mahabharata; Book of the Beginning”.