This is the only movie for which Elvis Presley did not record a new soundtrack. All the songs had been recorded between 1960-63, and had already been released on several albums or singles.
While filming, Elvis Presley gave his Sony film camera to director Norman Taurog. At the time those cameras were rare in the US. Taurog liked the idea because he could shoot the scene himself and review it before it went for editing.
Elvis Presley made this film in a deal with floundering Allied Artists, in which he took a pay cut (still making $750,000) and did not record any new material in exchange for 50% of the film's profits. The film was a big earner, costing $1.5 million and grossing about $5 million worlwide. It was credited with saving Allied Artists from bankruptcy.
The authors of the film, Elwood Ullman and Edward Bernds, are most famous for writing many of the Three Stooges shorts and movies from the 1930s to 1960s.