Continuity mistake: When Kirk Douglas smashes through the chapel window near the end of the film, you can clearly see that the window isn't stained glass - it's colored paper. Or perhaps papier-mache of some sort.
Continuity mistake: In the final scene of the film, the level of the lager in the glasses varies considerably depending on the camera angle.
Continuity mistake: After the old man has brought his fish in - really only the skeleton, after the sharks and other fish have devoured the fish - he goes straight to bed. The next morning, the boy goes to the bar and asks for coffee, with milk and sugar. But when the boy pours the coffee into a small tin cup, it is black, not a drop of milk to be seen.
Continuity mistake: Ben kicks the tractor when he can't get it started, denting the grille, the next time we see the tractor the grille is straight.