How to see peer review comments when rejection letter does not list them?
Well, there isn't really anything you can do except ask the editor, since he/she is the only one who has them (except of course the reviewers themselves, whose identities are not and will not be known to you).  So if you want those comments, that's what you'll have to do.

Of course, it is possible that:


the paper was "desk rejected" by the editor and never sent out for review at all; or
this journal has a policy of not sharing reviewer comments; or
the editor has decided for some reason that in this case it is not appropriate to share the comments with you.