Exporting the review comments of a clip in different formats (PDF, Word or CSV) is possible with the metadata export option in Flow. 

In order to include the comments, you need to select 'Include Review Comments'.

Several choices are activated by default; simply deactivate them if you don't want to export this information.

Make sure to include the 'Description' column (part of default selection) for the actual annotations and comments to show in the export.