In Five Iron's typical fashion Proof contains the band's humour. "A New Hope" ends with the song "Kingdom of the Dinosaurs", the hidden track after the end of "Every New Day" features various slip-ups recorded over the tour, and the title itself has a double meaning. The word "Revolting" is used to mean "disgusting", or "starting a revolution". The revolution referred to, however, is one of the heart. According to Keith Hoerig this is "... a personal revolution that each individual partakes in the choices they make and the way they live their lives."
While Proof was designed to consist of fan favorites, it also marks the first appearance of "A New Hope." "A New Hope" was written about the Columbine High School massacre, which affected some members of the band on a personal level. The band often practiced at Micah Ortega's house, about a five-minute walk from the school, and his sister attended there at the time of the shootings.
For those who attended any of the concerts which were recorded to be potentially used as this live album, the band had pieces of paper at their merch booth where one could sign up to be registered as a "backup singer." While the final album used cuts from a variety of shows, all the people who filled out their names were mentioned in a large fold-out booklet that went with the album, listed under the title "backup singers." In total about 7,000 names were listed.