I have a flight form Canada to Brazil with no layovers ..?
not after the flight leaves except in rare emergency situations. Now before you leave, yes, that specific flight could be cancelled and you rebooked on a flight with a connecting flight
They *could*, but unless there is some sort of emergency on the plane or on the ground which affects your destination, then they will not. Flights are pretty set outside of emergencies which are rare. They need that plane where in Brazil to pick up passengers to go somewhere else within hours of when you arrive. The pilots also have more flying to do (same day or the next day typically.) Having a plane land in the wrong place really screws this stuff up.
Yes, the plane could make an emergency landing en-route. If you are asking whether sometime between now and when the flight leaves whether the airline will change your reservation, then the answer is unlikely. They might if something screws up their schedule right before the flight, such as the plane they needed for the route being broken or stuck somewhere or weather problems messing up their schedule. They could also change you if they decide to cancel that particular route (it is uncommon for an airline to discontinue a route after they have already sold tickets for it). If they did do that, the most likely way they could re-route you to stop in a third country would be to rebook you on a partner airline. For example, if you are flying Air Canada, you can't change planes in the US to another Air Canada flight because they don't have rights to fly from the US to anywhere other than Canada.
They could, but it's unlikely (it would cost the airline more)
Unlikely, unless there is an emergency forcing the plane to stop somewhere that wasn't planned. If there's a planned route change, they will tell you by the time you get to the airport.
Yes the could The chances are they wont
Can the plane be diverted or make an emergency landing during the flight? YES Do you have an option to get off the plane and remain in the air? NO This does happen on occasion and procedures are in place to deal with this on a case by case basis. TOO BAD for you if they land in some country that is looking for you. Basic procedure is you land at alternate place and local officials deal with the situation. They have no desire to keep you and arrangements are made by the Airline to get you to destination. By one of their planes or on other Airlines that have available capacity to assist. You MIGHT be required to do a Passport check and a Customs inspection should this stopover be a longtime and passengers leave the Airport terminal. Just to take off a passenger needing medical assistance that can be done too. The rest of the passengers remain on the plane. The situation for medical assistance is dealt with and the flight continues obviously arriving late to final destination. There is not one rule for every possible situation you can dream up. Each incident is dealt with as it is. Your desired destination Airport could close to arrivals for many reasons. A storm, some security incident, debris on the runway or whatever. The pilot then goes where directed by ATC. As it costs lots of money for an unplanned stop Airlines only do it when it is necessary not on some random whim of the Pilot wanting to see some other Airport. It does not matter that the flight is to Brazil, Mexico or Argentina. The same basic procedure is used by all Airlines during international flights.
There's an Air Canada flight from Toronto that travels NON STOP to Bogota