Every single one of those old PDFs, especially OCRs, are full of errors, now corrected in this edition. There's a long history of errata, old and recent, and in

Every single one of those old PDFs, especially OCRs, are full of errors, now corrected in this edition. There's a long history of errata, old and recent, and in which editions they were corrected, at feynmanlectures.info