Romney said he was unaware of any provision that gives companies a tax deduction for moving operations overseas.

There is, but it is pretty small beer given the attention Democrats pay to it. The nonpartisan Joint Committee on Taxation estimated that ending the deduction for moving operations overseas would raise just $168 million over a decade. 

In the federal government, with an annual budget deficit of more than $1 trillion, that's what you call a rounding error.