Both Robert Webber and Al Lettieri's voices were dubbed by other actors in the English language version.
This is the first one of the Inspector Rizzo movie series (the second one is Um Tira Enrolado (1980)) where Bud Spencer exercises his swimming talents. Here Spencer, being an Olympic swimmer for Italy in 1952, 56 and 60, crosses the harbor of Macau by swimming.
This film marked the first time Bud Spencer was allowed to use his own voice on screen, due to his character sharing his Neapolitan background. He did so again for the remaining two movies in the Piedone series.