Joe Biden slipped up in his State of the Union address last night when he accidentally invited Americans to fly with him on Air Force One to Russia. The President, who spoke for over an hour in his speech to Congress, repeatedly stumbled over his words as he outlined his achievements in office and sought to contrast himself to Donald Trump. In a speech which was accused by critics of being more akin to a campaign speech than a traditional State of the Union, the 81-year-old momentarily referred to Moscow when criticising the cost of American prescription drugs, before quickly realising his err…