The legislative blitz that rocketed the $1.5 trillion tax cut through Congress in less than two months created a host of errors and ambiguities in the  law that businesses big and small are just now discovering and  scrambling to address. Companies and trade groups are pushing the Treasury Department and Congress to fix the law’s consequences, some intended and some not, including provisions that disadvantage certain farmers, hurt restaurateurs and retailers and could balloon the tax bills of large multinational corporations.