The women drank a lot of duty-free alcohol in the rest room, lit a cigarette, triggered the fire alarm, got into a fight and ended up making threats against the plane, said Janine Chapman, marketing director of the airline Sunwing.
The threat against the aircraft "was considered non-credible given their condition," she said in an email.
The plane returned to Toronto and the women were taken into custody, she wrote.
The passengers were provided with a different plane and the airline apologised. It had endured a similar incident a month ago.
The North American Aerospace Defense Command had scrambled two CF-18 fighter jets out of Quebec to escort Sunwing Flight 656 back to Toronto in yesterday's incident, a spokeswoman said.
In late July a Sunwing plane full of vacationers headed for Panama had to return to Toronto, escorted by two US F-16s, because of threats from a passenger.
Social media reports said that in the new incident the two women were apparently in their 20s.
"Once the aircraft was safely on the ground, the Canadian fighters returned to their home base," a NORAD statement added.
NORAD is the joint Canadian and American command in charge of maritime warning, aerospace warning and aerospace control for the neighboring nations.