Blooper

In the scene where Lupin saves Lady Clarisse from the shooters you can tell that the license plate ID changes continuously on all cars.

After Lupin and Jigen enter Cagliostro, the camera zooms out for a bit and shows them with their disguises off before they actually remove them a moment later.

As Lupin is pointing out the Count's castle to Jigen, the time shown on the clock tower jumps from 7:10 to 7:20 between shots.

Lupin's skin tone changes from fair to medium (pink) multiple times throughout the film, most prominently when he consoles Clarisse near the end of the film.

Count Cagliostro's hair color changes from light brown to dark brown several times throughout the film (due to an animation mistake).

In the clock tower, Lupin undoes a bolt by turning it clock-wise.

Due to misidentification, Richard Epcar is credited with providing the voice of Goemon for the Animaze/Manga dub in the credits of Discotek Media's DVD. The voice was actually provided by Michael Gregory, who is credited on Discotek's Blu-ray.

A newspaper clipping bears the date "Mercredi [Wednesday], 12 Septembre, 1968." However, September 12, 1968 was actually a Thursday.

Due to improper positioning of animation cels, Jigen's legs and feet appear for a brief moment in front of the grass as he gets into the car at the end of the opening credits sequence.

When Clarisse wakes up while she and Lupin are dangling over a cliff face, her eyes do not have pupils.

A newspaper clipping is shown that misspells the name Cagliostro as "Caligostlo".

In the Streamline dub, Jodo is portrayed throughout the film by Jeff Winkless, but in the climax, he is voiced by Kerrigan Mahan. This is due to the localization team believing that these were two separate characters (Mahan's portrayal is credited to "Goemon's Final Opponent" on the cast sheet").

The Streamline dub has Zenigata incorrectly giving first name as "Keibu" (which means "inspector" in Japanese). Zenigata's first name is actually Kouichi, and he has no reason to introduce his titles in both French and Japanese.

The Japanese ICPO delegate has an over-the-top accent, even though he has the same nationality as Zenigata.