General
Man With A Mission features a slide guitar.
Song meaning
Brett: "Man With A Mission is about two and a half minutes, just kidding. Cult figures that people follow mindlessly and how it's not a good idea to do that."[1]
Brett: "Man on a mission [he got the title wrong] is not autobiographical per se, but the character in the song represents a cult leader type".
References
^ Roger Vulture interview with Brett (1996)