The opening sequence, which is a simple montage of Lupin and Jigen driving around in their Fiat before setting up camp for the night just outside Cagliostro's border, set to the oddly somber song "Fire Treasure". It's such a stark contrast with everything that happens right before and after, yet sets the film's tone perfectly.
When Lupin and Jigen are being chased by ninjas in their car, they pile on the souped-up subcompact car and the rogues have to get them off. How do they do that? Simple, they maneuver near a wall, put the car into a side-wheelie and they literally scrape them off!
"So help me, Count, if you lay one slimy finger on Clarisse, your precious ring is gonna end up like this!" *fake ring explodes into confetti in the Count's hand*
The entire climax of the film in and around the clock tower is both one for the animators and Lupin. After the terrific chase and fight amongst the gears, he manages to beat the Count by giving him exactly what he wants.
The moment when Lupin and his gang stop the Count's wedding. When the Count's men seemingly skewer him and then move on to do the same to the others, that is when Lupin pulls off his masterstroke and gets ahold of Clarisse and the rings when and where the Count least expected it. Clearly, underestimating Arsene Lupin III is suicide even when the Big Bad is at the height of his power.