No, HBO was not filming a time-traveling episode at a Boardwalk Empire set in Greenpoint on Wednesday. The armed officers dropping from choppers were members of the NYPD’s Emergency Service Unit participating in hostage rescue drills. DNAinfo and the Post report that college students (who have reason to be wary of objects overhead in the city) in the NYPD Cadet Corps played civilians on the ground during mock raids on the show’s Ritz Carlton, styled like the Atlantic City hotel. It was all in the name of training for dire situations but the scene had to have alarmed at least a few onlookers who didn’t get the memo, including one woman who wrote on Twitter, “So apparently the choppers flying around Greenpoint all morning were the NYPD raiding Boardwalk Empire for terrorists.” Check out the Post’s footage.