What did the cross at the end mean?

The cross was discovered on one of the boats.
He got the cross as a reference; that what they experienceed in the past timeline actually happend.

X ~We are the people our parents warned us about

SPOILERS.....




In the very beginning, when we are introduced to Benirall and Ackerman, they are looking at a corpse removed from the ship in a body bag. The corpse was the sailor from Columbus' ship who was "pulled over" when the Benirall ship appeared out of the fog and passed the Spanish ships. The Spanish Cross is in with the body.

My guess...that Benirall sent it with the check to Howard as a way for Howard to "prove " his news articles.

Also, in response to another thread here about "what was with Colombus " when Benirall is giving the "ghost tour " of his ship to the team, he reads from Colombus ' ship log, about seeing a giant metal behemoth or something to that effect implying that a ship had passed through the Bermuda Triangle to Columbus' time.