So as to not be too repetitive, having a third party review certain key documents that you may be bias towards as well as having different technicians perform testing/assembling according to the testing/assembling documents to ensure they are relatively dummy proof since the worst case scenario could be failure of a product while under specification defined in a testing procedure.
Also reviewing the questions and concerns that may have been brought up earlier in the project but were disregarded at the time because they were deemed unimportant or not real concerns to ensure that at the completion stage with all that we know the concerns still do not apply. One thing to be aware of is that simply reading the documents can have several biases so do not lose sight of why you are reading/reviewing the documents. Having a copy of company policies or checklists of things that should be checked for each document type you are reviewing can help shift the view point to a more objective one.
The project as a whole for launching a product will require members from all divisions/departments at certain points and having those individuals check the documents using their departments protocols/procedures will help ensure compliance with regulations and internal policies as well as prevent the PM from overlooking certain things simply because they didn’t know certain facts about all the relevant regulations/policies.