Originally Posted by
YOWgary
Air Canada uses 2xxx flight numbers mainly to denote 'rescue' or 'replacement' flights in the event of cancellation, diversion etc, or - my best guess in your case - the original flight is so extremely delayed that virtually anybody aboard will have blown their onward connections.
For pedantic completeness, they'll also do it in the event of a day-of-flight significant downgauge (e.g. A321 is now an A320, they swapped in a JETZ fin on a mainline flight, etc.) that requires rebooking a lot of pax. Doesn't appear to be this case though.