The difference is that little details in the Van Halen setup actually mattered, whereas this minor typo probably makes zero difference in the overall scientific validity of a work into which it's been copy/pasted.
The brown M&Ms themselves could not have caused a serious problem, but were a sign of attention not being paid in an environment where serious problems could occur.
The same is true of the scientific papers mentioning "Gr". Everyone knows what the formula should be (it doesn't directly invalidate the paper), but seeing that implies a lack of attention (and that lack of attention is reason to cast skepticism upon the paper).
