To complete a job together in a responsible manner, everyone involved must be able to freely point out problems or each other's mistakes.
Do not let an attitude of "it's good enough" prevail. You must frankly discuss "what is the right thing to do." It is a mistake to be aware of shortcomings or errors and hesitate to point them out, for fear of being disliked or spoiling workplace harmony.
You must have the courage to frankly call things as you see them, even if that makes you unpopular. By doing so, you build trust in each other and create an environment for doing the best job possible.