Well this is a big "oops."

Nearly $21,000 in casino money is missing after it fell from the roof of an armored truck in New Jersey.

The truck picked up the money from the soon-to-be-closed Revel casino, according to The Press of Atlantic City.

Surveillance video showed the bag of cash on top of the truck's roof as it left the casino. It was still there when the truck left the Resorts Casino Hotel nearby.

It's not clear where the bag went missing.

A spokesman for GardaWorld armored car services told The Associated Press it is investigating and cooperating with authorities.