Jack Livesey claimed he was in the Parachute regiment of the British Army, did five tours of duty in Northern Ireland, and won a military medal. He was a guest of honor at the 25th anniversary commemorations of the Falklands War.
But the British Ministry of Defense says, "Jack Livesey (DOB 15/05/54) only served in the British Army in the Army Catering Corps from December 1971 until April 1974."
Livesey also claims he was a miltary adviser to Saving Private Ryan, though he wasn't paid a fee which is why, he says, there was never any public acknowledgment of his help. [BBC News]