http://goo.gl/maps/9RqdD
The arrow on this just looks way too long to me. Its almost as if they were trying to justify it with the legend. Thank god they didn't use the full spelling of Marlborough
Marlboro. ugh. 
Isn't the arrow on that sign supposed to be the one pointing to the upper-right? Like the ones on overhead exit signs?
One of the peculiarities of MassDPW/MassHighway guide sign standards. As the sign in question is inside the gore of an entrance ramp to a freeway, it's treated like an oversized "paddle" sign - hence the horizontal arrow as opposed to a slanted one.
As for Marlboro vs. Marlborough, the shorter spelling is still understood by drivers, and MassHighway was probably able to knock a foot or two off the panel width. Not a big deal with only one sign, but when you consider the typical Massachusetts signing project has between 200 and 300 major guide signs alone, that difference can add up quickly.