I know there are several but these affect the bassline. On So What, it sounds to me like PC is playing a natural D on the ascending intro figure over the Eb-7(@1:02) rather than Db as in the Real Book transcription. Wouldn't that make it a Melodic minor rather than a Dorian? On Impressions it is clear that the bass is playing the mix G7 and Ab7 rather than dor D-7 and Eb-7 as would be implied by the Real Book transcription. Try it the next time some tenor player calls it at a jam. It really changes the feel of the tune.