When viewing the details of a closed report, normally a red box indicates that the report is already closed. However, this red box is triggered by the post_reported field of the post being 0, which may not be the case as a new report on the same post may have been filed. Same goes for private messages. I really think this box should be shown based on the report_closed field of the report itself. It gets confusing when comparing a new report to previous reports on the same item.
Edit: also, by the same error, the "Close report" button may be shown on reports that are already closed. I intend to fix that as well.