You can't judge The Big Dig by 21st-century standards of comedy, and certainly not by 21st-century standards of political correctness. A fellow escapes from an insane asylum and merrily upsets the order of things in Tel Aviv. We don't even call them insane asylums any more, and we certainly don't laugh at the patients' behavior. Nor, for that matter, at the accents of minority groups, nor at overly friendly relationships between bosses and secretaries.
But those were different times. Kishon's point was to satirize the bureaucracy, always a timely target, and he recruited an impressive cast of Israeli comedians although his most impressive feat, spoken of with awe to this day, was to realistically recreate a large, well-known Tel Aviv intersection on a movie lot-- and flood it with water. In terms of scale, that makes The Big Dig the Ben Hur of Israeli comedies.
The movie isn't too well integrated-- for example, the reaction shots sometimes seem pasted in-- but the actors know what they're doing and they do it well, notably including Bomba Tzur in a lead role that requires him to be amusing without amusing lines.
