What can I sue the pilot for??? I was a TSA screener at the airport and I was terminated for an alleged theft.?

From a "common sense" point of view, considering you returned the wallet immediately, you may have a case for unfair dismissal. Your best course of action would be to consult a lawyer/solicitor who deals with employment law. It also appears that the pilot was trying to take advantage of the situation and may be guilty of slander.