The scene in which Kowalski and Colomba provoke Paco to a fistfight, including a pig-mud bath and over-the-top slapstick.
Corbucci called Il mercenario a picaresque, so there is by concept some humour in the film, but in this scene it is totally out of balance in an otherwise brilliantly balanced film. Somehow he even “outbalanced” the more serious looking Quien sabe?. 
Il mercenario is different form Django and The Great Silence, but it is a not less cynical film, despite a foxing light-heartedness.