Jed leaves the room to call Mark. Moments later, however, when they're speaking, Mark is in a phone booth. Jed couldn't have known the number of a public phone booth, let alone a phone booth where Mark Templeton just happened to be.
Mark tells Elly that the next time she sees him, he will be in "mufti". Mufti is a term for civilian clothes worn by a person who ordinarily wears a military uniform. It is an Arabic word, literally meaning "magistrate"; there is no indication how it came to mean civilian clothing.