Maybe, but still. Even in second world war, whenever there were enemy bombers approaching a strategical target, at least a hundred AA cannons (most likely flak88mm) bombed the sky to shot it down with rather poor accuracity (and those cannons could take down tanks with one shot, most likely one of the most dangerous cannon used at this period of time).
Even if the chariot wasn't moving in this scene, it is very, very odd that an old cannon managed to hit it. In battle between knights, both sides shot many cannons at once in a large area with hope that it will hit the target in (in game terms, with splash damage). It is just really weird that someone managed to use a cannon to snipe an air unit, even for a cartoon. (You would need to shot at least 20 of those with hope that one bullet will hit the target, you never snipe with old cannons, they are just not accurate and cannot be aim with such precysion).