The flight from Las Vegas was evacuated after landing safely.
The plane was then searched by police using sniffer dogs.
Passengers are now expected to stay in Montreal overnight before continuing their onward journey on Thursday.
Officials at the Airways said in a statement that the decision to divert the aircraft was made as a "precaution".
The company said it will provide hotel rooms for the passengers and rebook them "as soon as as we can".
It added it was cooperating with Canadian authorities.
