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:
Moderator flag notifications should reach mobile
Please can we have mod functionality added to the android/ios mobile apps or the mobile browser
Do moderator flags exist as mobile app notifications?
Why is mobile version of the site missing flag comment functionality
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?