What are any two common mistakes in a post-project lessons-learned meeting?

What will be an ideal response?

The author presents three common errors:
Misidentifying systematic errors. It is human nature to attribute failures or mistakes to external causes, rather than internal reasons. Closely related to this error is the desire to perceive mistakes as one-time or nonrecurring events. Rather than looking at our project management systems to see if the mistakes could be the result of underlying problems with them, many of us prefer the easier solution of believing that these results were unpredictable, that they were a one-time occurrence and not likely to recur, and that therefore we could not have prepared for them and do not need to prepare for them in the future.
Misapplying or misinterpreting appropriate lessons based on events. A related error of misinterpretation occurs when project team members or those reviewing the project wrongfully perceive the source of an encountered problem. Sometimes the correct lessons from a terminated project are either ignored or altered to reflect a prevailing viewpoint.
Failing to pass along lessons-learned conclusions. Although it is true that an organization's projects are characterized as discrete, one-time processes, they do retain enough areas of overlap, particularly within a single firm's sphere, to make the application of lessons-learned programs extremely useful.