When Rex and Peter find themselves in "the big shootout", stuck in a canyon below 20 ornery gunmen, Rex announces "I made a mistake. We can't beat this many men. Usually about 40% chicken out." If 40% of the 20 gunmen had chickened out, that would leave 12 of them — and Rex had two revolvers containing 6 bullets each.
The film's title, Rustler's Rhapsody, doesn't seem to make much sense in regards to the actual content of the film (no form of rustling factors into the plot, nor does any form of rhapsody appear)... until you realize that "Rustler" could be considered a near synonym for "cowboy" and a "Rhapsody" is a type of song. The title literally refers to the film genre and character type it's paying homage to (the Singing Cowboy), just with Added Alliterative Appeal. note They probably didn't simply call this "The Singing Cowboy" so as to not be confused with the Gene Autry film of the same name.
