You will notice that the broadarrow is punched just like the other details. The fillets (red arrows) prove that. To punch a detail like that would require expensive equipment and tooling. This is not something your average faker would have.
Compare this with the engraving on the watch in your picture. It is crisp, with no fillets. It is very clearly CNC engraving or etching. The trouble is, CNC controlled engraving and laser etching has become very accessible now. Even some respectable brands use laser etching. The bottom line is, HMT themselves have no memory of having supplied watches to the military. It does not take much to refinish a dial with the broadarrow and have one etched on the case back.