So I am getting ready to book a trip for a friend and myself to go to Costa Rica. He never had a passport before so he had to get one (came in yesterday). He sent me a picture of it. Because it didn't list a middle name I assumed he didn't have one. So I passed his information to the travel agent to book flights for both of us (we are originating in different cities). Then he tells me he does have a middle name but apparently he didn't put it on the application.

Will it be an issue if his plane ticket has his middle name but his passport will not? Or is it best just to leave his middle name off his ticket? I don't want him to have any hassles when he checks in for his flight and with TSA.