If you have opened a document revision you will be able to see the download and new revision icons towards the top right.
Access required: Write
The action menu to the right of the icons can look something like this:
Download latest published revision
The download icon and hamburger menu action on a document page download the latest revision of the document, even if you are looking at a previous revision you will get the latest revision with this action.
If you want to download previous revisions of a document you can do so in the revisions menu of the right information menu.
Same action as in the documents list
Actions that have the same behavior as in the documents list include: