According to the Hal B. Wallis papers at the AMPAS Library, Frank Gorshin tested for the role of Cookie and both Russ Tamblyn and Johnny Carson were considered but the filmmakers decided to go with an older actor who could be a "breezy conniver with the girls" in order for the character to be portrayed successfully.
All of the main cast scenes were filmed in Hollywood on indoor sets, in front of process screens, and on backlots. Location and exterior shots were filmed in Germany, but they used stand-ins and were intercut with the process-screen shots.
The songwriting team of Jerry Leiber and Mike Stoller wrote two song for the movie, "Dog Face" and "Tulsa's Blues", but later withdrew the songs when they didn't like the royalty payments contract that Elvis' manager Col. Tom Parker insisted that they sign.
The song "Wooden Heart" is a cover version of the famous German folk song "Muss i denn zum Städtele hinaus" (Must I then go away to the town), of which Elvis Presley also sang a few lines in his version. The song was first released in the 1830s. Elvis Presley's version was a big hit in Germany and about 400 000 records were sold within a few weeks. However The Bavarian Radio broadcast and the Westberlin-radio broadcast were boycotting this version due to "deliberated Schmultzyness of German folk songs" and because the stations wanted to broadcast serious folk music.
The song "Tonight is so right for love" is based on the aria "Barcarole" by Jacques OFfenbach from his opera "The mermaids of the Rhine" from 1864. Due to copyright issues in Europe an alternative version was released based on "Geschichten aus dem Wiederwald" by Johann Strauß.