Currently, neither can comments be flagged from the mobile version of SE web pages, nor do moderators receive any notification of flags (most moderator tools are unavailable). The work-around is to switch to the desk-top version.
Furthermore, it'd be an undoubted boon for moderators to be able to learn about flags' being raised—high-priority ones at any rate—through the Android/iOS notifications system.
There have been several feature requests concerning these matters already, e.g. the following:
Clearly it's good if rude or abusive comments in particular are flagged & deleted as quickly as possible. Given that inclusion efforts have been prioritized, will SE be looking again at these feature requests?