The problem with textbooks is that they leave the student with an unreasonable degree of faith in the infallibility of textual resources. When you’re in an undergraduate physics course, for example, practically every detail of anything that you learn has been settled for almost a hundred years; you are never going to find any flaw in the derivation of Kepler’s laws of motion or the damped modes of a harmonic oscillator.
This cannot, however, carry neatly over to the field of original research. Case in point, I just wasted a week of time because a couple of authors way back in 1985 left a typo in their paper and all of the subsequent authors to cite their findings were just too damn tactful to point it out (or, indeed, didn’t notice).
I’m not honestly certain how some flaws like that manage to make it, not only past peer review, but through generations of subsequent re-readings without anyone calling them out on it. I suspect that this just goes to confirm that physicists are just as lazy as anyone else. I suspect that the only reason I noticed is because of my own tendancy to obsess over minor details.