"McGuffin" is a Hollywood term for an item which a majority of the plot centers around the characters trying to find and/or protect, but which has minor significance to the plot itself (the Holy Grail in Indiana Jones and the Last Crusade (1989)). Hence, the money and the body which are found and lost at the beginning of this film, are the title's "Double McGuffin".
"Live (For Today)" and "Somebody Who Really Cares", the first and last songs of the movie, were performed by Dion Pride, who also played Specks in the film.
When Specks is buying a newspaper, a radio announcer is heard commenting on the performance of the football player Lyle Alzado. Lyle Alzado played Assassin #2 in the film.
Despite being marketed as a "family" film, "from the creator of 'Benji", there's an alternate opening scene which contains a very brief glimpse of female nudity, seen through a sniper's rifle sight.