Revealing mistake: Underdog's first costume is supposed to be a felted down (the more accurate term would be fulled) wool sweater. When wool is felted the stitches lose clear definition and usually achieve a "felted" look. It is clear that the sweater in the movie has just been switched for another smaller sweater as the stitches are still sharply defined after it has been pulled from the dryer. This is especially clear around the U. No attempt to make the smaller sweater look "felted" was made. This refers to the original costume with the solid white U, not the second costume with the yellow outlined U.