Flagged. Should I take this information to Legal?

Your question is very misleading, the explanation should have started with the whole story that you received an article 15.

You are post Art15 and in the punishment phase. You are required to be flagged during the punishment phase. Your time to object was prior to accepting the non judicial punishment. If you took any proof to legal nothing would happen because you elected to accept the article 15. Instead You could have chosen to prove your innocence in a trial by court martial, but if found guilty you may have had prison time or a felony conviction. You could also appeal the decision, but you will already be finished with your extra duty before the appeal authority even reviews your case.

here is a truth. technicalities can be corrected. What is important, is this, did you do, or not do, whatever the FLAG is for, if that can be proven, then its just a minor adjustment. Another aspect is, and you do not say in your description, is this NJP or a Court Martial. If it is a company or summarized Art. 15, and your alleged offense can be proven, are you sure you want to push for a trial by Court Martial over a mere technicality, which would then be corrected in the court, and you would still be on the wrong end of a decision, one in which can have a felony conviction, depending on the offense.

Second, if this IS part of an Art. 15 proceeding, you have 24 hours between the CSM/1SG reading you the Art.15, and the Commander imposing Judgement, in which you are specifically instructed to go to TDS, who goes over the documents with you. It is there that you point out any issues with the document(s). You failing to do this, does not constitute an unfair judgement.

Third, when you see the Commander, he will ask if you have any information, to include a witness, in which there would be a mitigating circumstance, or presents something that would effect the outcome of his judgement. If you did have this information, and failed to present it, and then signed the documents, then its a done deal. Do the time, and then drive on.

and last, if this is just a simple FLAG, while they are still considering pushing an Adverse Action up through legal for an Art. 15, or gathering the relevant documents to include in the packet, or if the Commander is thinking of a Bar To Re-enlistment, you will receive another counseling, in which you have the opportunity to correct the error.

As I have pointed out, you have ample opportunities to correct any discrepancies in the proceedings, multiple opportunities to see legal, present it to the Commander, and speak to your first line supervisor, who will be counseling you. It seems to me that you are looking for a way to circumvent punishment, or corrective action. I tell you this from experience, as I have stepped on my crank a few times and know the NJP process, from both initiating them, and receiving them.

1. Anytime you have a problem like this go to Legal. 2. Be advised it's an easy fix for both sides and you can still be flagged, 3. Since you didn't say that you didn't do it I surmise that they had every right to flag you. Remember they are giving you a chance to soldier out of the flag, with nothing permanent on your record.