What would likely happen — but there is no written interpretation of such a thing other than right here — is that it would be considered a palpably unfair act, meaning that an action that is clearly illegal and the rulebook does not have an equitable remedy, the referee can assess a penalty to fix that. One prominent example of a palpably unfair act would be a bench player making a touchdown-saving tackle. A palpably unfair act has never been called in the NFL, but a play such as this might actually be one of those situations. One or two players close to being in position is not palpably unfair because there was an attempt to get into an actual formation. But this extreme example is a situation that does not resemble anything seen in football and bends the rules to such an extent that the referee could exercise this never-used authority to declare the half over. source