The discussion highlights a potential error in the last line of Chapter 7 in Goldstein's Classical Mechanics 3rd Edition, where the equation p = p' is questioned regarding the momentum in different inertial frames. Participants clarify that while forces and masses remain constant, momentum should differ due to varying velocities between frames. An erratum for the 2nd edition exists, but the 3rd edition has significant changes that complicate its application. Equation (7.2) is identified as needing correction, and the term "vakonomic" is clarified after initial confusion over its spelling. Overall, the newer editions of Goldstein are noted to contain serious conceptual errors that warrant caution.