Back in my proofreader days, I happened to catch a major error simply because the graphs didn’t make sense. According to the document handed to me that day, the United Arab Emirates ranked much more highly than the United States in various measures of freedom. As it turned out, a row had been transposed on the spreadsheet, rearranging the scores of every nation studied, and we kicked the document back to start.
The point is that these things are bound to happen (especially as companies increasingly decide to forgo professional editors), but it would be nice if they were promoted as highly in error as in statement:

So what explained the anomaly? GISS’s computerised temperature maps seemed to show readings across a large part of Russia had been up to 10 degrees higher than normal. But when expert readers of the two leading warming-sceptic blogs, Watts Up With That and Climate Audit, began detailed analysis of the GISS data they made an astonishing discovery. The reason for the freak figures was that scores of temperature records from Russia and elsewhere were not based on October readings at all. Figures from the previous month had simply been carried over and repeated two months running.