I wonder how "mind you" should be analyzed. Quirk et al. (1985) call it a comment clause. Beyond calling it a comment clause, what can we say? I was debating whether to deem it an imperative or a subjunctive(eque) statement like "Bless you," "Thank God," or "**** you." Like the latter statements, we can't use the reflexive (viz., "Take care of yourself"). "Bless you" doesn't mean "Bless yourself."
Upon further reflection, however, it does seem to me that "mind you" is an imperative. I suspect "you" works like "ye" in the King James "Haste ye"-style imperatives, which were used when the second-person pronoun inflected for case and number. In other words, I suspect that "mind you" works as "mind ye" would work if we could still use "ye." But, then, if that's so, we should also be able to drop the pronoun altogether. And, indeed, some folks do. From the COCA corpus:
". . . a quaint English village. Not a real English village , mind , but the kind in which Miss Marple might . . . ."
" 'Personally , mind , I find it shocking, really shocking,' she said."
"You'll have no trouble hearing news from home. Old news , mind , but news just the same."
"Oh, all right, it was a public lavatory. Quite sizable , mind , but even so."
"'Just a kiss of the whip , mind ,' Simenon told him; 'a reminder that he must not cross me'"
"We neglected the fireplace, the cooking, the goats. But , mind , they also had a feeling that something special was going to happen."
PS to R2: When searching COCA, one must use a space before and after a comma.