Ambiguity is a manufacturing problem
Two outlines, missing drill definitions or conflicting thickness notes can stop an otherwise manufacturable design. Start the review by checking that the release package describes one board at one revision.
Geometry must match the selected process
Trace, space, drill, annular-ring and copper-to-edge rules interact with material, thickness and copper requirements. A feature accepted in one construction may not be appropriate in another. Use production rules confirmed for your actual stack-up.
Assembly issues start in layout
Insufficient access, ambiguous polarity and unsuitable footprints can turn into placement or soldering problems. Review component orientation and inspection access before the final board outline and density make changes expensive.
Testing needs physical access
A test plan that relies on inaccessible nodes may not provide the intended coverage. Review probe access, programming connections and fixture requirements during design, not after the assembled boards arrive.
Treat review as a closed loop
Record the issue and the accepted solution, update all affected outputs and issue a new revision where necessary. An email approval that is absent from the manufacturing package can be lost on the next order.