Bruce Lee was the martial arts adviser for this film. He also was brought in to train and teach Sharon Tate with her martial arts scenes.
Dean Martin was so distraught over the murder of his The Wrecking Crew (1968) co-star and friend Sharon Tate in August 1969, six months after the movie was released, then still playing in theatres in the US and opening internationally, that he abandoned the next already announced "Matt Helm" motion picture series installment (to be titled "The Ravagers") and never played the character again. This is contrary to the widely held opinion that the series ended due to poor reviews and box office.
Exteriors at 141 S. Carolwood Drive in Holmby Hills were used for the chateau owned by the Count Contini character. Built in 1936 the estate was known as 'Owlwood'. Co-founder of 20th Century Fox Studios Joseph Schenck, Tony Curtis and Sonny Bono & his then wife Cher are some of the famous people who have owned the estate over the years. At the time "The Wrecking Crew" was made, the place was owned by Tony Curtis who was friends with Dean Martin and Sharon Tate, both of whom starred in the film.
In the closing credits as had been done with prior Matt Helm films, the next Helm film was announced, titled The Ravagers. That film was never made. The Wrecking Crew was the last of the Helm films.