If your Publication link has previous publication revisions, you can choose to show them when previewing it in the Web Player. You need to turn on the appropriate option from the publication context menu.
Once the option is on from the Dashboard / Publications context menu, all the document Editors will have access to the publication revisions panel on the Web player.
Note: Publication revisions(s) are available to all Editors that have access to that document.
When viewing a previous version, you can see its comments at that point in time but cannot add new comments or replies. You can only do that in the latest version.