1) The Seder Hadoros writes in the Hakdama, why his
Sefer is so important, because without the knowledge
of history even Gedolim made mistakes. (he names
some of them)
2) R. B. Epstein in his Sefer Mekor Baruch points out
a major mistake the Seder Hadoros made by continuing
two sentences as one.
3) .R.B. Epstein in his Sefer Torah Temimah made
a major mistake, the exact type as the Seder Hadoros.
The Mussar Haskel is , by pointing mistakes others
made, you will end up doing the same.
Last week I pointed out two mistakes of others.
Last week, I made two mistakes I know of.