I can find vague references from various sources (e.g. on Talk:Anti-vandalism ideas: Automatic vandalism identification) implying that Wikipedia edits can be flagged as potential vandalism. However, I (a normal, non-admin Wikipedia user) don't see any way to flag a given Wikipedia edit as potential vandalism. Am I missing something?
You don't "flag" edits, per se. If you see an edit that is vandalism, you're expected to "rollback" or, at least, edit out the vandalism bits yourself. That's part of Wikipedia's mantra of Be Bold!
If an account is a serial vandal, there are places to report them so that they can be dealt with.