PAA, the footnote in Michtav M’Eliyahu says that Chazal’s halachos were inherently correct, but not for the reasons they said. Presumably this means that they had a mesorah as to the din, but not the reason.
The Dor R’vii just says the halacha remains even if we find factual errors. He does not say why, he just says it is so. R’ J.D. Bleich, IIRC, suggests it’s because the Hashgochah Elyonah caused them to pasken a certain way, and the halacha is this way because the fact that at chasimas haSha”s it was paskened this way shows that the halacha is true.
What Slifkin says, that the authority of Chaza’l must be upheld even though they were wrong, makes a mockery out of halacha.
It should be noted that the Chazon Ish writes (Kovetz Igros Vol. 1, 15) that saying Chaza’l erred in halacha or aggada is, according to our mesorah, kefirah.