Mylène Demongeot later claimed that a fourth episode called "Fantomas à Moscou" ( "Fantomas in Moscow") was planned to follow, but apart from the fact that Jean Marais was tired of feeling second billed after the then confirmed star Louis de Funès, the project failed to materialize because the trio of leading actors had grown far too expensive.
Only the opening scene was shot in Scotland. The main crew stayed in France during the whole shooting between Château de Roquetaillade, near Bordeaux, and Fontainebleau Forest.
Although the scenes are supposed to happen in Scotland, note that the cars are left-driven. (see explanation above)
Jacques Dynam Jacques Dynam (Inspector Bertrand) was fourth-billed in the previous two movies as his character has a lot of screen time. In this movie, he is 12th in the cast, even behind actors who have only one scene like Robert Dalban (newspaper director) and Rita Renoir (cameo getting off the plane).
Out of the three films, this installment is the darkest when it comes to the body count and the plot overall. Therefore part three is the closest in its tone to the original Fantomas novels which follow the Gothic / homicidal maniac vibe, not the comic one.