A cook found the note, written in black marker, behind a urinal pipe next to a stall in the men's bathroom at Bowlero just before 10 p.m. Saturday, Capt. Shawn Kudlacik said.
The business was evacuated and Paterson Avenue briefly closed down.
The Bergen County Sheriff's Bomb Squad and K-9 Unit swept the building without finding anything, eventually allowing patrons and employees to return, Kudlacik said.
Detectives checked surveillance cameras and interviewed workers, as well.
"There are no disgruntled former employees suspected," the captain said.
Ironically, workers who cleaned the bathroom several times during the day didn't see the note, he said.
Click here to follow Daily Voice Jersey City and receive free news updates.