in hindsight

(say sth) with hindsight or in hindsight (thinking about the past with the knowledge one now has) — задним числом, ретроспективно; оглядываясь на прошлое

Example 1: We should never have bought this car. It's been nothing but trouble. — It's easy to say that with hindsight.

Example 2: In hindsight, it was easy to determine what I had done wrong in the job interview.

Note: Another way of saying with hindsight is in retrospect.

See also
[hindsight is always twenty-twenty]