In my own field, George Will gets the very concept of State Capitalism wrong to hate on Obama.
In the field of climate change, George Will gets the very facts wrong, claiming a past global cooling consensus from a paper whose very point is that there was never a global cooling consensus.
And just today, George Will is upset over the very idea of changing transportation within this country, singling out my birth city of Portland, Oregon as this dreaded, unattainable dystopia where people bike to work. Most notably, he hyperbolizes that we will never reach a point where 0.01% of Americans bike to work. However, 0.4% already do, a number "forty times larger than a percentage that Will deems unrealistically utopian." (Edit: wonkette has a nice angry take on the transportation issue as well)
So, dear readers: can you find another example of George Will deliberately getting facts wrong in a field that isn't Keynesian economic policy, global warming, or transportation? Comment with any and every example you can find, hopefully in a "new field, new error" format. It'd be nice to have a comprehensive list of this online.