This movie was part of a deal that Elvis Presley's manager, Col. Tom Parker, signed with NBC and National General Films. Elvis was paid a large sum for doing both the NBC TV Special (Elvis (1968)) and this picture for National General. The TV special was shot at the end of June 1968 (and aired in December) and the film was shot in July and August 1968 (and was released early 1969). The TV show was supposed to be a Christmas Special with Christmas songs only but turned to be a rock-'n'-roll revival show while the movie, on the contrary, was supposed to be much more violent.
There's a nude scene where Ina Balin leaves the bathtub as Elvis' character appears in her room. This scene is rarely seen, and is generally not in the edits of the film that have been televised or on video/DVD.
Promotions for this film included 25 Southwestern cities which held "Charro Girl" contests, with finalists appearing in Dallas and Austin. In Austin, "Charro! Day" was hosted by the then Governor Preston Smith. Likewise, the governors of Oklahoma and Louisiana declared "Charro! Day" in honor of previews in their states. A number of actors from the film traveled to appearances at these sneak previews.
The songs were recorded in November 1968 at the Goldwyn Studios. "Charro", the title song, appeared on the B-side of Elvis Presley's single "Memories" (1969). A second song, "Let's forget about the Stars", written by A.L. Owens, was recorded for but not used in the film. It appeared, among others, on the compilation album "Let's Be Friends" (1970).
Elvis Presley was really keen on the project, as it afforded him the chance to break out of the rut of cheap musicals he had been turning out. This was his opportunity to be seen as a serious actor but he was hugely disappointed when he showed up on the first day of filming to find that the script had been completely rewritten and was a pale shadow of what he had originally signed on for. Contractually, he was obligated to fulfill the role.